UC-NI 


SAN    FRANCISCO 


for  its  coming  righ 
intelligent  teacher 
recommend  it. 


"  In  a  very  sma! 
whole  History  of  t 
office  in  this  count 
possible  in  a  narra 
thousands  of  even 
historical  periods- 
pire,  that  of  Charl' 
tive.  We  can  end' 
From  Prof.  WM.  P 

u It  is  very  hare 
how  to  teach  and  \ 
is  necessary,  and  r, 
From  R.  M.  LUSHJ 

"  This  Manual  i 
effect  a  reform  in  t 
chronological  reca 
From  Pi 

"  Your  Manual 
and  subjected  to  tl 
It  is  tlie  best  corny 

subject  in  the  choice, "ancr^rr'arrgcmciu  01  mt!  aetans,  m  me  cieuinesg  ana  Minpiicuy  of 
the'language,  in  the  omission  of  the  endless  and  uninteresting  minutiae  with  which  many 
text-books  on  this  subject  are  cumbered,  you  have  been  highly  successful.  Unlike  most 
compends  of  history,  the  narrative  is  well  connected  and  pleasing,  thereby  attracting 
rather  than  repelling  the  student.  Nor  are  the  maps  among  the  least  valuable  features  of 
the  book.  You  have  fully  recognized  the  principle  that  the  Study  of  History  and  Geog- 
raphy should  go  hand  in  "irand It  is  extremely  gratifying  to  find  a  book  that 

furnishes  the  pupil  with  the  leading  facts  of  history  in  so  attractive  a  manner,  and  leaves 
to  the  teacher  so  large  an  opportunity  for  oral  instruction." 

Published  by  Clark  &  Maynard,  5  Barclay  St.,  New  York, 


ANDERSON'S  SCHOOL  HISTORIES. 

Anderson's  Pictorial  School  History  of  the  United  States. 

By  JOHN  J.  ANDERSON,  A.  M.,  Late  Principal  of  Grammar  School 
No.  31,  New  York  City;  Author  of  a  Grammar  School  and  other 
Histories  of  the  United  States,  and  of  a  Manual  of  General  History. 
Beautifully  illustrated  with  about  two  hundred  maps,  portraits,  vignettes, 
etc.  "With  an  appendix  containing  the  Constitution  of  the  United 
States,  with  questions  and  explanations,  and  the  Declaration  of  Inde- 
pendence. 12mo.  400  pages. 

The  distinctive  features  of  this  work  are : — 1st.  A  system  of  maps,  with  map  questions 
and  references,  combining  the  geography  with  the  chronology,  thus  teaching 'byAhe  eye 
as  well  as  the  ear,  and  consequently  making  the  impression  upbii  the  memory  more4ast-%' 
ing.  2d.  A  second  set  of  questions  differing  entirely  from  the  first.  The'se," by  associat- 
ing facts  belonging  to  the  same  class  or  train  of  events,  require  answerp  o£  a  topical 
character,  and  thus  compel  the  student  to  review  his  lessons  witbthoughtfiflness. 


From  the  Hon.  H.  H.  VAN  DYCK,  former  Superintendent  of  Public.  Instruot&m  for' the 

State  of  New  York.  r 

"The  books  comprising  Anderson's  Series  of  School  Histories  have-^een  in  my  pos- 
session during  the  last  six  months.  I  have  examined  them  with  considerable  care,  and 
find  them  works  of  decided  merit.  There  is  a  directness,  clearness,  and  conciseness  in 
the  statements,  and  an  admirable  method  connected  with  the  chronological  and  geogra- 
phical features  of  the  narrative,  that  commend  them  to  my  judgment.  To  the  instructor 
who  aims  at  thoroughness  in  the  knowledge  imparted  to  his  pupils  of  our  country's 
history,  these  books  arc  certainly  invaluable.  I  recommend  them  without  reservation.'" 

From-C.  B.  PARSONS,  D.  D.,  LL.D.,  Chairman  of  Coinmittee  of  Examination  and  Control 

of  Public  Schools,  Louisville,  Ky. 

"I  have  carefully  examined  the  'Pictorial  History  of  the  United  States,'  by  John  J. 
Anderson,  and  unhesitatingly  pronounce  it  the  best  of  its  kind  that  has  fallen  under  my 
observation.  Its  remarkable  comprehensibility,  so  concisely  given,  "  multum  inparvo, 
with  its  excellent  arrangement  of  adaptation  to  the  purposes  of  instruction,  canuot  fail 
to  recommend  it  to  general  use.  I  most  cordially  approve  of  its  introduction  into  our 
schools." 

From  Rev.  J.  M.  ANDERSON,  Principal  of  Ohio  Female  College,  College  Hill,  Ohio. 

"The  book  stands  well  the  most  careful  scrutiny.  I  am  particularly  pleased  with  the 
fairness  of  its  statements  as  to  the  results  of  battles,  etc.  The  history  of  our  country  is 
rich  enough  in  great  deeds  to  warrant  the  historian  in  telling  the  whole  truth,  and 
nothing  but  the  truth,  as  to  her  reverses  and  misfortunes.  Without  truth,  history  is  a 
delusion  and  a  snare.  In  point  of  method,  clearness,  and  succinctness  of  narration, 
also,  I  regard  this  book  as  incomparably  the  best  manual  of  the  kind  that  has  appeared. 
None  but  a  practical  and  experienced  teacher  could  have  produced  such  a  model  class- 
book.  We  shall  lose  no  time  in  introducing  it  into  this  Institute." 

From  Miss  JANE  A.  BARTHOLOMEW,  the  luell-knoivn  teacher  of  History  in  the  Connecticut 

State  Normal  School. 

"  In  respect  to  symmetry  of  plan,  proportionate  arrangement  of  matter,  correctness, 
clearness,  and  conciseness  of  statement,  and  in  variety  or  explanatory  information,  it  is 
superior  to  any  other  text-book  in  United  States  history  used  here.  The  seals  of  the 
States  and  miniature  maps,  are  valuable  additions  to  the  book ;  while  the  charts  and 
questions  for  review,  condensing  gradually,  as  they  do,  its  whole  contents,  meet  a  want 
which  many  teachers  have  neither  the  means  nor  ability  to  supply." 


PUBLISHED     BY 


NEW    YORK. 


THK  VISCERA  IN  POSITION. 


TREATISE 


ON 


PHYSIOLOGY  AND  HYGIENE 


FOR 


EDUCATIONAL  INSTITUTIONS  AND  GENERAL 
READERS. 


FULLY  ILLUSTRATED. 


JOSEPH   C.   HUTCHISON,  M.  D., 

President  of  the  New  York  Pathological  Society,  Vice- President  of  the  New  York 

Academy  of  Medicine,  Surgeon  to  the  Brooklyn  City  Hospital,  late  President 

of  the  Medical  Society  of  the  State  of  New  York,  etc. 


NEW     YORK: 

CLARK   &   MAYNARD,   PUBLISHERS, 

5  BARCLAY  STREET. 

1872. 


4 


<xy 


Entered  according  to  Act  of  Congress,  in  the  year  1870, 

By  CLARK  &  MAYNARD. 
In   the   Office  ol  the  Librarian  of  Congress,    at   Washington, 


EDUCATION 


Stereotyped  by  LITTLK,  KKNMK  A  Co.. 
846  and  647  Broadway. 


TO    MY    WIFE, 


'WHOSE     SYMPATHY     HAS,     TOR     MORE     THAN     TWENTY     YEARS,     LIGHTENED     THB 
CARES     INCIDENT     TO 

AN  ACTIVE  PROFESSIONAL   LIFE, 

THIS   HUMBLE    VOLUME 

IS     AFFECTIONATELY     INSCRIBED. 


543488 


PREFACE. 


THIS  work  is  designed  to  present  the  leading  facts  and  principles 
of  human  Physiology  and  Hygiene  in  clear  and  concise  language, 
so  that  pupils  in  schools  and  colleges,  and  readers  not  familiar  with 
the  subjects,  may  readily  comprehend  them.  Anatomy,  or  a  de- 
scription of  the  structure  of  an  organ,  is  of  course  necessary  to  the 
understanding  of  its  Physiology,  or  its  uses.  Enough  of  the  former 
study  has,  therefore,  been  introduced,  to  enable  the  pupil  to  enter 
intelligently  upon  the  latter. 

Familiar  language,  as  far  as  practicable,  has  been  employed, 
rather  than  that  of  a  technical  character.  With  a  view,  however, 
to  supply  what  might  seem  to  some  a  deficiency  in  this  regard,  a 
Pronouncing  Glossary  has  been  added,  which  will  enable  the  in- 
quirer to  understand  the  meaning  of  many  scientific  terms  not 
in  common  use. 

In  the  preparation  of  the  work  the  writer  has  carefully  examined 
all  the  best  material  at  his  command,  and  freely  used  it ;  the  special 
object  being  to  have  it  abreast  of  the  present  knowledge  on  the  sub- 
jects treated,  as  far  as  such  is  possible  in  a  work  so  elementary  as 
this.  The  discussion  of  disputed  points  has  been  avoided,  it  being 
manifestly  inappropriate  in  a  work  of  this  kind. 

Instruction  in  the  rudiments  of  Physiology  in  schools  does  not 
necessitate  the  general  practice  of  dissections,  or  of  experiments  upon 
animals.  The  most  important  subjects  may  be  illustrated  by  draw- 


4  PEEFACE. 

ings,  such  as  are  contained  in  this  work.  Models,  especially  those 
constructed  by  Auzoux  of  Paris,  dried  preparations  of  the  human 
body,  and  the  organs  of  the  lower  animals,  may  also  be  used  with 
advantage. 

The  writer  desires  to  acknowledge  his  indebtedness  to  R  M 
WYCKOFF,  M.D.,  for  valuable  aid  in  the  preparation  of  the  manu- 
script for  the  press;  and  to  R.  CRESSON  STILES,  M.D.,  a  skilful 
microscopist  and  physician,  for  the  chapter  "  On  the  Use  of  the 
Microscope  in  the  Study  of  Physiology."  Mr.  AVON  C.  BURNHAM, 
the  well-known  teacher  of  gymnastics,  furnished  the  drawing  of 
the  parlor  gymnasium  and  the  directions  for  its  use. 

Brooklyn,  N.  Y.<  1870. 


CONTENTS. 


CHAPTER  I. 

PAGE 

THE    FRAMEWORK  OF   THE    BODY 15 

The  Bones — Their  form  and  composition — The  Properties  of  Bone — The 
Skeleton — The  Joints — The  Spinal  Column — The  Growth  of  Bone — 
The  Repair  of  Bone. 

CHAPTER  II. 
THE    MUSCLES 26 

The  Muscles — Flexion  and  Extension — The  Tendons — Contraction — 
Physical  Strength — Necessity  for  Exercise — Its  Effects — Forms  of 
Exercise  —  Walking  —  Riding  —  Gymnastics  —  Open-air  Exercise — 
Sleep — Recreation. 

CHAPTER  III. 
THE    INTEGUMENT,  OR   SKIN 4 

The  Integument — Its  Structure — The  Nails  and  Hair — The  Complexion 
— The  Sebaceous  Glands — The  Perspiratory  Glands — Perspiration 
and  its  uses — Importance  of  Bathing — Different  kinds  of  Baths — 
Manner  of  BatJiing — The  Benefits  of  the  Sun — Importance  of 
Warm  Clothing — Poisonous  Cosmetics. 

CHAPTER  IV. 

THE    CHEMISTRY  OF   FOOD 53 

Tne  Source  of  Food — Inorganic  Substances —  Water — Salt — Lime — Iron 
— Organic  Substances — Albumen,  Fibrin,  and  Casein — The.  Fats  or 
Oils — The  Sugars^  Sfaich,  and  Gam — Stimulating  Substances- 
Necessity  of  a  Regulated  Diet. 


CONTENTS. 


CHAPTER  V. 

PAG15 
FOOD    AND    DRINK 64 

Necessity  for  Food — Waste  and  Repair — Hunger  and  Thirst — Amount 
of  Food — Renovation  of  the  Body — Mixed  Diet — Milk — Eggs — Meat 
— Cooking — Vegetable  Food — Bread — The  Potato — Fruits — Purity 
of  Water— Action  of  Water  upon  Lead—Goffer,  Tea,  and  Chocolate 
— Effects  of  Alcohol. 

CHAPTER  VI. 

DIGESTION 80 

The  Principal  Processes  of  Nutrition — The  General  Plan  of  Digestion — 
Mastication — The  Teeth — Preservation  of  the  Teeth — Insalivation 
— The  Stomach  and  the  Gastric  Juice — The  Movements  of  the 
Stomach — Gastric  Digestion — The  Intestines — The  Bile  and  Pan- 
creatic Juice — Intestinal  Digestion — Absorption  by  means  of  Blood- 
vessels and  Lacteals — The  Lymphatic  or  Absorbent  System — The 
Lymph — Conditions  which  affect  Digestion — The  Quality,  Quan- 
tity, and  Temperature  of  the  Food — The  Influence  of  Exercise  and 
Sleep. 

CHAPTER  VII. 
THE    CIRCULATION 101 

The  Blood — Its  Plasma  and  Corpuscles — Coagulation  of  the  Blood — The 
Uses  of  tJie  Blood — Transfusion — Change  of  Color — The  Organs  of 
the  Circulation — The  Heart,  Arteries,  and  Veins — The  Cavities 
and  Valves  of  the  Heart — Its  Vital  Energy — Passage  of  the  Blood 
through  the  Heart — 1  he  Frequency  and  Activity  of  its  Movements — 
The  Pulse — The  Spygmograph — TJie  Capillary  Blood-vessels — The 
Bate  of  the  Circulation — Assimilation — Injuries  to  the  Blood-vessels. 

CHAPTER  VIII. 
RESPIRATION 123 

The  Objects  of  Respiration — TJie  Lungs — The  Air- Passages— Vie  Move- 
ments of  Respiration — Expiration  and  Inspiration — TJie  Frequency 
of  Respiration — Capacity  of  the  Lungs — The  Air  ice  Breathe— 
Changes  in  the  Air  from  Respiration — Changes  in  the  Blood — In- 
terchange of  Oases  in  the  Lungs — Comparison  between  Arterial  and 


CONTENTS.  7 

Venous  Blood — Respiratory  Labor — Impurities  of  the  Air — Dust — 
Carbonic  Acid — Effects  of  Impure  Air — Nature's  Provision  for 
Purifiying  the  Air —  Ventilation — Animal  Heat. 

CHAPTER  IX. 

PAGE 

THE    NERVOUS    SYSTEM 148 

Animal  and  Vegetative  Functions — Sensation,  Motion,  and  Volition — 
The  Structure  of  the  Nervous  System — The  White  and  Gray  Sub- 
stances— The  Brain — Its  Convolutions — The  Cerebellum — The  Spi- 
nal Cord  and  its  System  of  Nerves — The  Anterior  and  Posterior 
Roots — TJie  Sympathetic  System  of  Nerves — The  Properties  of  Nerv- 
ous Tissue — Excitability  of  Nervous  Tissues — The  Functions  of  the 
Spinal  Nerves  and  Cord— The  Direction  of  the  Fibres  of  the  Cord — 
Reflex  Activity  and  its  Uses — The  Functions  of  the  Medulla  Oblon- 
gata  and  the  Cranial  Ganglia — The  Reflex  Action  of  the  Brain. 

CHAPTER  X. 

THE    SPECIAL    SENSES 177 

The  Production  of  Sensations — Variety  of  Sensations — General  Sensi- 
bility— Pain  and  its  Function — Special  Sensation,  Touch,  Taste, 
Smell,  Sight,  and  Hearing — The  Hand,  the  Organ  of  Touch — The 
Sense  of  Touch — Delicacy  of  Touch — Sensation  of  Temperature  and 
Weight — The  Tongue  t/ie  Organ  of  Taste — The  Nerves  of  Taste — 
The  Sense  of  Taste,  and  its  Relations  with  the  other  Senses — The 
Influence  of  Education  on  the  Taste — The  Nasal  Cavities,  or  the 
Organs  of  Smell — The  Olfactory  Nerve — The  Uses  of  the  Sense  of 
Smell— The  Sense  of  Sight— Light— The  Optic  Nerve— The 
Eyeball  and  its  Coverings — The  Function  of  the  Iris — The 
Sclerotic,  Choroid,  and  Retina — The  Tears  and  their  Func- 
tion— The  Movements  of  the  Eyeball — The  Function  of  Ac- 
commodation—  The  Sense  of  Hearing  and  Sound— The  Ear,  or 
the  organ  of  Hearing — The  External,  Middle,  and  Internal  Ear. 

CHAPTER  XI. 

THE    VOICE 227 

Voice  and  Speech — Ihe  Larynx,  or  the  Organ  of  the  Voice — The  Vocal 
Cords— The  Laryngoscope— The  Production  of  the  Voice— The  Use 
of  the  Tongue— The  different  Varieties  of  Voice— The  Change  of 
Voice — Its  Compass — Purity  of  Tone —  Ventnloquy. 


b  CONTENTS. 

* 

CHAPTER  XH. 

FAOB 
THE    USE    OF   THE    MICROSCOPE    IX    THE    STUDY  OF 

PHYSIOLOGY 236 

The  Law  of  Tissues — Necessity  of  the  Microscope — Different  kinds  of 
Microscopes — Additional  Apparatus — Preliminary  Studies — The 
Study  of  Human  Tissues — Tissues  of  t?ie  Inferior  Animal* — Incen- 
tives to  Study. 

APPENDIX. 

POISONS    AND   THEIR    ANTIDOTES ,  .  ,  .  -    .  ^,        247 

GLOSSARY ^52 


LIST  OF  ILLUSTRATIONS 


FRONTISPIECE, 
VISCERA  IN  POSITION, 

1.  Section  of  bone,  17 

2.  Structure  of  bone,  magnified,  ....         17 

3.  The  skeleton,  .  , 18 

4.  Cells  of  cartilage, 20 

5.  Elbow-joint,  .         , 21 

6.  Spinal  column, 22 

7.  The  muscles,  ........     24 

8.  Muscular  tissue,  magnified,         .         •£     •         •         •         25 

9.  Biceps  muscle  of  the  arm,        ....  .26 

10.  View  of  knee-joint,      .......         27 

n.  Appliance  for  strengthening  the  muscles,        .         .         -35 

12.  Appliance  for  strengthening  the  muscles,  35 

13.  Parlor  gymnasium, 36 

14.  Root  and  transverse  section  of  hair,  magnified,    .         .         43 

15.  Granules  of  potato  starch,        .         .         .         .         .         .61 

1 6.  Section  of  the  trunk, 81 

17.  Section  of  a  tooth,  .         .         .         .         .         .         .82 

1 8.  Section  of  the  jaws, 82 

19.  Section  of  the  jaws — right  side, 84 

20.  Structure  of  a  salivary  gland,        .....         87 

21.  Head  of  a  horse,  showing  salivary  gland,  etc.          .         .     87 

22.  Section  of  chest  and  abdomen,  .         .         .  .         90 

23.  Organs  of  digestion,        .         .         .         .         .         .  91 

24.  The  lacteals, 97 

25.  Blood  corpuscles,    .         .         .         .         .         .         •         .102 

26.  Blood  corpuscles  of  man  and  lower  animals,       .         .    -      103 

27.  Circulation  of  the  blood,         .         .         .         .         .         .   108 


10  LIST   OF   ILLUSTRATIONS. 

FIG.  PAGE 

28.  Heart  and  large  vessels, 109 

29.  Section  of  the  heart, 1 10 

30.  Form  of  the  pulse, 116 

31.  Valves  of  the  veins,         .         .         .         .         .         .         .  117 

32.  Web  of  frog's  foot,  magnified, 119 

33.  Circulation  in  a  frog's  foot, 119 

34.  Organs  of  the  chest, 124 

35.  Larynx,  trachea,  and  bronchial  tubes,     .         .         .         .125 

36.  Diagram  of  the  structure  of  the  air-cells,    .         .         .  125 

37.  Section  of  the  lungs,       .         .         .         .         .         .         .126 

38.  Section  of  mouth  and  throat, 127 

39.  Ciliated  cells, 128 

40.  Cerebro-spinal  system,       .         .         .         .         .         .  151 

41.  Upper  surface  of  the  cerebrum, 153 

42.  Vertical  section  of  the  brain, 154 

43.  Base  of  the  brain, 155 

44.  Brain  and  spinal  cord,        .         .         .         .         .         .  156 

45.  Sense  of  touch, 185 

46.  Section  of  nasal  cavity, 193 

47.  Front  view  of  th^^ye,     .......  200 

48.  Vertical  section  of  eye,       ......  202 

49.  Diagram  for  blind  point  of  eye, 207 

50.  Retinal  image,           .         .         .                  .         .         .  210 

51.  Different  shapes  of  the  globe  of  the  eye,  .         .          .212 

52.  Function  of  accommodation, 214 

53.  Diagram  of  the  ear, 218 

54.  Section  of  the  ear, 221 

55.  Section  of  larynx  and  trachea,         .                            .  229 

56.  View  of  vocal  cords  by  the  laryngoscope,  .          .         .  232 

57.  Different  positions  of  vocal  cords, .232 

58.  Simple  microscope, 238 

59.  Compound  microscope, 239 

60.  Household  microscope,      ......  240 

61.  Popular  microscope., 241 


INTRODUCTION. 


THE  Human  Body  is  the  abode  of  an  immortal  spirit, 
and  is  the  most  complete  and  perfect  specimen  of  the 
Creator's  handiwork.  To  examine  its  structure,  to  ascer- 
tain the  uses  and  modes  of  action  of  its  various  parts, 
how  to  protect  it  from  injury,  and  maintain  it  in  a 
healthy  condition,  is  the  design  of  this  work. 

The  departments  of  knowledge  which  are  concerned 
in  these  investigations,  are  the  science  of  Human  Physi- 
ology and  the  art  of  Hygiene. 

PHYSIOLOGY  treats  of  the  vital  actions  and  uses  of  the 
various  parts  of  living  bodies,  whether  vegetable  or  ani- 
mal. Every  living  thing,  therefore,  has  a  Physiology. 
We  have  a  Vegetable  Physiology,  which  relates  to  plants ; 
and  an  Animal  Physiology,  relating  to  the  animal  king- 
dom. The  latter  is  also  divided  into  Comparative  Physiol- 
ogy, which  treats  of  the  inferior  races  of  animals,  and 
Human  Physiology,  which  teaches  the  uses  of  the  various 
parts  of  the  human  body. 

HYGIENE,  or  the  art  of  preserving  health,  is- the  practi- 
cal use  of  Physiology.  It  teaches  us  how  to  cultivate  our 
bodily  and  mental  powers,  so  as  to  increase  our  strength 
and  to  fit  us  for  a  higher  enjoyment  of  life.  It  also  shows 
us  how  to  prevent  some  of  the  accidents  which  may  befall 
the  body,  and  to  avoid  disease.  It  is  proper  that  we  should 


13  INTRODUCTION. 


understand  the  construction  and  powers  of  our  bodies ;  but 
it  is  our  duty,  as  rational  beings,  to  know  the  laws  by  which 
health  and  strength  may  be  maintained  and  disease  warded 
off. 

There  are  various  means  by  which  we  gain  important 
information  respecting  the  Physiology  of  man.  Plants 
aid  us  in  understanding  the  minute  structure  of  the  hu- 
man body,  its  circulation,  and  absorption.  From  inferior 
animals  we  learn  much  in  respect  to  the  workings  of  the 
different  organs,  as  we  call  those  parts  of  the  system  which 
have  a  particular  duty  to  perform.  In  one  of  them,  as  in 
the  foot  of  the  frog,  we  can  study  the  circulation  of  the 
blood;  in  another,  we  can  study  the  action  of  the  brain. 

By  vivisection,  or  the  laying  bare  of  some  organ  of  a 
living  animal,  we  are  able  to  investigate  certain  vital 
processes  which  are  too  deeply  hidden  in  the  human  body 
to  be  studied  directly.  This  is  not  necessarily  a  cruel 
procedure,  as  we  can,  by  the  use  of  anaesthetics,  so  blunt 
the  sensibility  of  the  animal  under  operation,  that  he 
need  not  suffer  while  the  experiment  is  being  performed. 
There  are  other  means  by  which  we  gather  our  informa- 
tion. There  are  occasionally  men,  who,  from  some  acci- 
dent, present  certain  parts,  naturally  out  of  view,  in 
exposed  positions.  In  these  cases,  our  knowledge  is  of 
much  greater  value  than  when  obtained  from  creatures 
lower  in  the  scale  of  being  than  man. 

We  are  greatly  aided,  also,  by  the  use  of  various  instru- 
ments of  modern  invention.  Chief  among  these  is  the 
microscope,  which  is,  as  we  shall  learn  hereafter,  an  ar- 
rangement and  combination  of  lenses  in  such  a  way  as 
greatly  to  magnify  the  objects  we  wish  to  examine. 


INTRODUCTION. 


We  have  much  to  say  of  Life,  or  vital  activity,  in  the 
course  of  our  study  of  Physiology ;  but  the  most  that  we 
know  of  it  is  seen  in  its  results.  What  Life  is,  or  where  its 
precise  position  is,  we  are  not  able  to  determine.  We  dis- 
cover one  thing,  however,  that  all  the  parts  of  the  body 
are  united  together  with  wonderful  sympathy,  so  that  one 
part  cannot  be  injured  and  other  parts  not  suffer  damage. 
It  is  further  evident  that  all  organs  are  not  equally  im- 
portant in  carrying  on  the  work  of  Life;  for  some  may 
temporarily  suspend  their  action,  without  serious  results 
to  the  system,  while  others  must  never  cease  from  acting. 
Yet  there  is  nothing  superfluous  or  without  aim  in  our 
frames,  and  no  part  or  organ  can  suffer  harm  without 
actual  loss  to  the  general  bodily  health.  On  this  point 
Science  and  Holy  Writ  strictly  agree. 


PHYSIOLOG-Y, 


AND 


HYGIENE. 


CHAPTER  I. 
THE  FRAMEWORK  OF  THE  BODY. 

Tlie  Bones — Their  Form  and  Composition — The  Properties  of  Bone — 
Tlie  Skeleton— Tlie  Joints— The  Spinal  Column— The  Growth  of 
Bone — The  Repair  of  Bone. 

1.  The   Bones. — The   framework  which   sustains  the 
human  body  is  composed  of  the  Bones.    The  superstructure 
consists  of  the  various  organs  on  which  the  processes  of 
life  depend.     These  organs  are  soft  and  delicately  formed, 
and,  if  unprotected,  would,  in  most  cases,  rapidly  be  de- 
stroyed when  subjected  to  violence,  however  slight.      The 
bones,  having  great  strength  and  power  of  resistance,  afford 
the  protection  required. 

2.  The  more  delicate  the  organ,  the  more  completely  does 
Nature  shield  it.     For  example :  the  brain,  which  is  soft  in 
structure,  is  enclosed  on  all  sides  by  a  complete  box  of  bone ; 
the  eye,  though  it  must  be  near  the  surface  of  the  body 
to  command  an  extensive  view,  is  sheltered   from  injury 
within  a  deep  recess  of  bone;  the  lungs,  requiring  freedom 
of  motion  as  well  as  protection,  are  surrounded  by  a  large 
case  of  bone  and  muscle.     The  bones  serve  other  useful 
purposes.     They  give  permanence  of  form  to  the  body,  by 

1 .  The  framework  of  the  body  ?    The  superstructure  ?    Softness  and  delicacy 
of  the  organs  ?    How  protected  ? 

2.  The  more  delicate  the  organ  ?    Example  in  relation  to  the  brain  ?    The  eye  ? 
The  lungs  ?    The  services  performed  by  the  bones  ? 


1C  -     fll-E   FRAMEWORK   OF  THE   BODY. 


holding  rhe  softer  parts  in  their  proper  places.  They 
assist  in  movement,  by  affording  points  of  attachment  to 
those  organs  which  have  power  of  motion — the  muscles. 

3.  The  Form  and  Composition  of  the  Bones.— 
Their  shape  and  size  vary  greatly  in  different  parts  of  the 
body,  but  generally  they  are  arranged  in  pairs,  one  bone  for 
each  side  of  the  body.     They  are  composed  of  both  mineral 
and  animal  substances,  united  in  the  proportion  of  two 
parts  of  the  former  to  one  of  the  latter ;  and  we  may  sep- 
arate each  of  these  substances  from  the  other  for  examina- 
tion.     First,  if  we  expose  a   bone   to  the  action  of  fire, 
the  animal  substance  is  driven  off,  or  "  burned  out."     We 
now  find  that,  though  the  shape  of  the  bone  is  perfectly 
retained,  what  is  left  is  no  longer  tough,  and  does  not  sus- 
tain weight  as  before.     Again,  we  may  remove  the  mineral 
portion,  which  is  a  form  of  lime,  by  placing  a  bone  into  a 
dilute  acid.     The  lime  will  be  dissolved  out,  and  the  shape 
of  the  bone  remain  as  before;  but  now  its  firmness  has 
disappeared,  and  it  may  be  bent  without  breaking. 

4.  If,  for  any  reason,  either  of  these  ingredients  is  dis- 
proportionate  in   the   bone   during   life,    the   body   is   in 
danger.     The  lime  is  useful   in   giving  rigidity  of  form, 
while  the  animal   substance  insures  toughness  and  elas- 
ticity.    By  their  union,  we  are  able  to  withstand  greater 
shocks   and  heavier   falls   than   would   be   possible   with 
either  alone.     In  youth,  the  period  of  greatest   activity, 
the  animal   constituent  is  in  excess:    a  bone   then   does 
not  break  so  readily,  but,  when  broken,  unites  with  great 
rapidity  and  strength.     On  the  other  hand,  the  bones  of 
old  persons  are  more  easily  broken,  and  in  some  cases  fail 
to  unite.     The  mineral  matter  being  then  in  excess,  indi- 
cates that  the  period  of  active  exertion  is  drawing  to  a 
close. 

3.  Their  shape  and  size  *    Of  what  composed?    Possibility  of  being  separated  ? 
Effect  of  fire  ?    Of  dilute  acid  ? 

4.  Effect  of  deficiency  of  ingredient  ?    Usefulness  of  the  lime  ?    Of  the  animal 
substance?    Effect  of  their  union  ?    Condition,  in  youth?    Old  age? 


THE    FRAMEWORK    OF   THE    BODY. 


1? 


5.  The  Structure  of  the  Bones. — If  we  examine  one 
of  the  long  bones,  which  has  been  sawn  through  length- 
wise, we  observe  that  it  is  admirably  fashioned  for  affording 


A.  Longitudinal     B.  Transverse  section  of  bone. 


FIG.  1.— SECTION  op  BONE. 

lightness  as  well  as  strength  (Fig.  1).  Its  exterior  is  hard 
and  resisting,  but  it  is  porous  at  the  broad  extremities, 
while  through  the  central  portion 
there  is  a  cavity  or  canal  which  con- 
tains an  oily  substance,  called  marrow. 
Let  us  now  take  a  thin  section  of 
bone,  and  examine  it  under  the  mi- 
croscope ;  we  discover  that  it  is  pierced 
by  numerous  fine  tubes  (Fig.  2), 
about  which  layers  of  bone-substance 
are  arranged.  Accordingly,  though  a 
bone  be  as  hard  as  stone  externally,  it 
is  by  no  means  as  heavy  as  stone,  by 
reason  of  its  light  interior  texture. 
Another  element  of  power  is  found  in 
the  curved  outline  of  the  bones.  The  pre  2 

curved  line  is  said  to  be  "  the  line  of          structure  of  bone  en- 
beauty,"  as  it  certainly  is  the  line  of  lar£ed- 
strength,  and  is  uniformly  employed 
in  the  bones  whose  position  exposes  them  to  accident. 


5.  In  what  respect  admirably  fashioned  ?    Its  formation?    Microscopic  exam 
Ination  ?    The  inference  ?    "  Line  of  beauty  ?" 


FIG.  3.— THE  SKELETON 


THE  FRAMEWORK  OF  THE  BODY.  19 

6.  The  Skeleton. — The  number  of  bones  in  the  human 
body  exceeds  two  hundred.    When  these  are  joined  together 
in  the  proper  places,  they  form  what  is  termed  the  Skeleton 
(Fig.  3).     It  embraces  three  important  cavities.     The  first, 
surmounting  the  frame,  is  a  box  of  bone,  called  the  skull; 
below  this,  is  a  bony  case,  or  "  chest ;"  anl  lower  down  is 
a  bony  basin,  called  the  pelvis.     The  two  latter  compose 
the  trunk.     The  trunk  and  skull  are  maintained  in  their 
proper  relations  by  the  "  spinal  column/'     Branching  from 
the  trunk   are   two  sets  of  limbs:   the   arms,   which   are 
attached   to  the  chest  by  means  of  the  "  collar-bone"  and 
"  shoulder-blade ;"  and  the  legs,  directly  joined  to  the  lower 
part  of  the  trunk. 

7.  The  cavities  of  which  we  have  spoken,  are  designed 
for  the  lodgment*  and  protection  of  the  more  delicate  and 
perishable  parts  of  the  system.     Thus,  the  skull,  together 
with   the   bones  of  the   face,  shelters  the  brain  and  the 
organs  of  four   senses — sight,  hearing,  smell,   and   taste. 
The  chest  contains  the  heart,  lungs,  and  great  blood-ves- 
sels, while  the  lower  part  of  the  trunk  sustains  the  liver, 
stomach,  and  other  organs 

8.  The  Joints. — The  point  of  union  of  two  or  more 
bones  forms  a  joint  or  articulation,  the  connection  being 
made  in  various  ways  according  to  the  kind  and  amount 
of  motion  desired.      The   movable  joints  are  compacted 
together  by  certain  strong  fibrous  bands,  called  ligaments. 
These  ligaments  are  of  a  shining,  silvery  whiteness,  and 
very  unyielding;  so  much  so,  that  when  sudden  violence 
is  brought  to  bear  in  the  vicinity  of  a  joint,  the  bone  to 
which  a  ligament  is  attached  may  be  broken,  while   the 
ligament  itself  remains  uninjured.      When  this   connect- 
ing material  of  the  joints  is  strained  or  lacerated  by  an  ac- 


6.  Number  of  bones?    Skeleton?    The  skull  ?    Chest?    The  trunk  ?    The  trunk 
and  skull,  how  maintained  ?     What  of  the  arms  ?    Legs  ? 

7.  Design  of  the  cavities  ?    Give  the  examples. 

8.  Joint  or  articulation  ?    Movable  joints,  how  compacted?    The  ligaments  of 
the  movable  joints  ?    What  is  a  sprain  ?    Consequence  of  a  serious  sprain  ? 


20  THE  FRAMEWORK  OF  THE  BODY. 

cident,  a  "sprain"  is  the  consequence.  An  injury  of  this 
sort  may  be,  and  frequently  is,  quite  as  serious  as  the 
breaking  of  a  bone. 

9.  The  ligament,  then,  secures  firmness  to  the  joint; 
it  must  also  have  flexibility  and  smoothness  of  motion. 
This  is  accomplished  by  a  beautiful  mechanism  the  perfec- 
tion of  which  is  only  feebly  imitated  by  the  most  ingenious 
contrivance  of  man.  The  ends  of  the  bones  are  covered 
by  a  thin  layer  of  cartilage,  which  being  smooth  and  elas- 
tic, renders  all  the  movements  of  the  joint  very  easy.  In 
addition  to  this,  there  is  an  arrangement  introduced  for 
"lubricating"  the  joint,  by  means  of  a  delicate  sac  con- 
taining fluid.  This  fluid  is  constantly  supplied  in  small 
quantities,  but  only  so  fast  as  it  is  used  up  in  exercise. 
In  appearance,  it  is  not  unlike  the  white  of  an  egg,  and 
hence  its  name  synovia,  or  egg-like. 

10.  Thus,  we  observe,  that  two 
very  different  substances  enter  into 
the  composition  of  a  joint.  The 
ligament,  very  unyielding,  affords 
strength,  while  the  cartilage,  elastic 
and  moist,  gives  ease  and  smooth- 
ness of  motion.  The  amount  of 
motion  provided  for  varies  greatly 
in  different  joints.  In  some  there  is 
none  at  all,  as  in  the  skull,  where 
jg»  one  bone  is  dove-tailed  into  another 
by  what  are  termed  sutures.  Others 
have  a  hinge-like  motion,  such  as 

Fro.  4.-CELLS  op  CARTILAGE.  faOSQ     Qf    ftie     elbow,    wrist,    ankle, 

and  knee;  the  most  complete  of  these  being  the  elbow- 
joint  (Fig.  5).  Belonging  to  another  class,  the  ball-and- 

9.  Office  of  the  ligament  ?   What  must  it  have  ?    How  accomplished  ?   Describe 

1   1  of  "what  do  we  observe  as  resards  the  composition  of  a  joint  ?    The  lament 
and  cart ilajre?    What  varies?    Example  of  the  skull?    Other  examples  ? 
ball-and-socket  joint? 


THE    FRAMEWORK   OF   THE    BODY. 


socket  joint,  is  that  at  the  shoulder,  possessing  a  freedom 
of  motion  greater  than  any  other  in  the  body. 


Fio.  5.— ELBOW  JOINT.    A,  Bone  of  the  arm ;  B,  C,  Bones  of  the  fore-arm. 

11.  The  Spinal  Column. — The  spjnal  column  is  often 
spoken  of  as  the  "  back-bone,"  as  if  it  were  a  single  bone, 
while,  in  reality,  it  is  composed  of  a  chain  of  twenty-six 
small  bones,  called  vertebra.  The  spinal  column  is  a 
wonderful  piece  of  mechanism.  It  not  only  connects  the 
important  cavities  of  the  body,  as  has  already  been  shown, 
but,  also,  itself  forms  a  canal,  which  contains  the  spinal 
cord.  The  joints  of  the  vertebrae  are  remarkable  for  the 
thick  layers  of  cartilage  which  separate  the  adjacent  sur- 
faces of  bone.  The  amount  of  motion  between  any  two 
of  these  bones  is  not  great;  but  these  little  movements, 
taken  together,  admit  of  very  considerable  flexibility,  in 
several  directions,  without  endangering  the  supporting 
power  of  the  column. 


11.  What  is  the  spinal  column  ?    What  docs  it  connect  and  form  ?    Joints  of 
the  vertebrae  ?    Amount  of  motion  ?    Result  ? 


22  THE  FRAMEWORK  OF  THE  BODY. 

12.  The  abundant  supply  of  intervertebral  cartilage  has 
another  important  use,  namely,  it  adds  greatly  to  the 
elasticity  of  the  frame.  It  is  due,  in  part, 
to  this  elastic  material,  and  in  part  to  the 
frequent  curves  of  the  spine,  that  the  brain 
and  other  delicate  organs  are  protected  from 
the  shock  of  sudden  falls  or  jars.  During 
the  day,  the  constant  pressure  upon  these 
joints,  while  the  body  is  erect,  diminishes 
the  thickness  of  the  cartilages;  so  that  a 
person  is  not  so  tall  in  the  evening  as  in 
the  morning.  The  effects  of  this  compres- 
sion pass  away  when  the  body  reclines  in  a 
horizontal  position. 

13.  The  Growth  of  Bone.— Bone,  like 
all  the  other  tissues  of  the  body,  is  con- 
stantly undergoing  change,  old  material 
being  withdrawn,  and  new  particles  taking 
their  place.  This  has  been  shown  conclu- 
sively by  experiments.  If  an  animal  be  fed 
with  madder — a  red  coloring  matter — for  a 
day  or  two,  the  bones  soon  become  tinged ; 
then,  if  the  madder  be  discontinued  for  a 
few  days,  the  original  color  returns.  If,  how- 
ever, this  material  be  alternately  given  and 
withheld,  at  short  intervals,  the  bone  will 
be  marked  by  a  succession  of  red  and  white 
rings.  In  very  young  animals,  all  the  bones 
become  colored  in  a  single  day;  in  older 
FIG.  6.— THE  ones,  a  longer  time  is  required.  The  process 
of  waste  and  repair,  therefore,  is  constantly 
taking  place  in  this  hard  substance,  and  with  astonishing 
rapidity. 

1 2.  Elasticity  of  the  frame  ?    Protection  of  the  brain  from  shocks      Tallness 
of  persons  ?    Effects  of  reclining  ? 

13.  Change  in  bone?    Example— animal  and  madder.     Rapidity  of  change  in 
color?    Waste  and  repair? 


• 


THE   FRAMEWORK   OF  TIJE   BODY.  23 

14.  The  Repair  of  Bone. — Nature's  provision  for 
uniting  broken  bones  is  very  complete.  At  first,  blood  is 
poured  out  around  the  ends  of  the  bone,  as  a  result  of 
the  injury.  This  is  gradually  absorbed,  and  gives  place 
to  a  watery  fluid,  which,  thickening  from  day  to  day,  ac- 
quires, at  the  end  of  two  weeks,  the  consistency  of  jelly. 
This  begins  to  harden,  by  a  deposit  of  new  bone-substance, 
until,  at  the  expiration  of  five  or  six  weeks,  the  broken 
bone  may  be  said  to  be  united.  It  is,  however,  still  fragile, 
and  must  be  used  carefully  a  few  weeks  longer.  The 
process  of  hardening  continues,  and  months  must  pass 
before  the  union  can  be  said  to  be  complete. 


QUESTIONS  FOR  TOPICAL  REVIEW. 

PAGE 

1.  What  useful  purposes  do  the  bones  serve  ? 15, 16 

2.  State  what  you  can  of  the  composition  of  the  bones 16 

3.  Of  the  usefulness  of  lime  in  the  bones 16 

4.  Of  the  usefulness  of  animal  substance  in  the  bones 16 

5.  State  what  you  can  of  the  structure  of  the  bones 17 

6.  Of  the  strength  belonging  to  the  bones '. 15. 16,  17 

7.  What  is  meant  by  the  human  skeleton  ? 19 

8.  Give  a  description  of  its  construction 19 

9.  What  is  meant  by  a  joint  in  the  human  frame  ? 19 

10.  State  what  you  can  of  the  movable  joints 19, 20 

11.  What  office  is  performed  by  the  ligaments  of  the  joints  ? 19,  20 

12.  What  by  the  cartilage  at  the  joints  ? 20 

13.  What  movable  joints  are  there  ? 20,  21 

14.  Describe  the  construction  of  the  spinal  column 21 

15.  What  properties  and  powers  does  the  spinal  column  possess  ? 21,  22 

16.  When  is  a  person  taller  than  at  other  times  ? . .        22 

17.  Give  the  reason  for  this 22 

18.  What  can  you  state  of  the  growth  of  bone  ? 22 

f  19.  Describe  the  process  by  which  a  broken  bone  is  repaired 23 

M        '  Jr'  w  ft  si 


y^x^v    -fc-t^ 

'* 


: 


THE   MUSCLES. 


FIG.  7.— TUB  MUSCLES. 


THE   MUSCLES. 


CHAPTER  II. 

THE  MUSCLES. 

The  Muscles— Flexion  and  Extension— The  Tendons— Contraction- 
Physical  Strength— Necessity  for  Exercise— Its  Effects— Forms  of 
Exercise  —  Walking — Riding  —  Gymnastics  —  Open-air  Exercise — 
Sleep — Recreation. 

1.  The  Muscles. — The  great  mass  of  the  body  exter- 
nal to  the  skeleton,  is  composed  of  the  flesh,  or  Muscles, 
which   largely  determines  its  outline   and   weight.     The 
muscles   are   the    organs   of  motion.      Their   number  is 
about  four  hundred,  and  to  each  of  them  is  assigned  a 
separate  and  distinct  office.    They  have  all  been  studied, 
one  by  one,  and  a  name  given  to  each,  by  the  anatomist. 
Each  is  attached  to  bones  which  it  is  designed  to  move. 
A  few  are  circular  in  form,  and  enclose  cavities,  the  size 
of  which  they  diminish  by  contraction. 

2.  If  we  examine  a  piece  of  flesh,  we  observe  that  it  is 
soft,  and  of  a  deep  red  color.     Its  structure  appears  to  be 

composed  of  layers 
and  bundles  of  small 
fibres.  Let  us  fur- 
ther examine  these 
fibres  under  the  mi- 
croscope. We  now 
discover  that  they 
are,  in  turn,  made  up 
of  still  finer  fibres, 
or  fibrillce :  these  are 

FIG.  8— MUSCULAR  TISSUE. 
a  6,  Striped  muecular  fibres:  c,  The  game  more     Seen   in  rig.  8.      ihe 

fibres  are  beautifully 

1 .  What  are  the  muscles  ?    Their  number  ?    The  design  of  most  of  them  ?    Of 
a  few? 

2.  The  structure  of  flesh?    Its  color,  etc.?    The  composition  of  the  fibres? 
How  marked?- 


THE   MUSCLES. 


-B 


marked  by  parallel  wavy  lines,  about  ten  thousand  to  an 
inch,  which  give  the  fibre  its  name  of  the  striped  muscular 
fibre.   All  of  the  voluntary  muscles  present  this  appearance. 
3.  Flexion   and  Extension.— The  muscles  are,  for 
the   most  part,  so    arranged   in   pairs,   or   corresponding 
sets,  that  when   motion  is  produced  in  one  direction  by 
one  set,  there  is,  opposite  to  it,  another 
muscle,   or    group   of   muscles,   which 
brings  the  limb  back  to  its  place.    When 
they  act  alternately,  a  to-and-fro  move- 
ment results.    When  a  joint  is  bent,  the 
motion  is  called  flexion;  and  when  it  is 
made  straight  again,  it  is  called  exten- 
sion.   When  both  sets  act  equally,  and 
at  the  same  moment,  no  motion  is  pro- 
duced, but  the  body  or  limb  is  main- 
tained in   a  fixed  position:  this  occurs 
when   we    stand   erect.      The    muscles 
which  produce  extension  are  more  pow- 
erful than  those  opposite  to  them. 

4.  The  muscles  are  also  distinguished, 
on  the  other  hand,  as  the  voluntary 
and  involuntary  muscles,  according  as 
they  are,  or  are  not,  under  the  control 
of  the  will.  The  heart  is  an  example  of 
the  involuntary  variety.  We  cannot 
change  its  action  in  the  least  by  an 
effort  of  the  will.  When  we  sleep,  and 
the  will  ceases  to  act,  the  heart  contin- 
ues to  beat  without  cessation.  The  voluntary  muscles, 
on  the  other  hand,  are  such  as  are  used  only  when  we  wisn 
or  will  to  use  them — as  the  muscles  of  the  hand  or  arm 
(Pig.  9). 


FIG.  9. — A,  Biceps  mus- 
cle of  the  arm:  B,  C, 
Its  tendons. 


3.  Arrangement  of  the  muscles?    Their  action  ?    Flexion  and  extension?    Ac- 
tion of  the  muscles  when  we  stand  erect  ? 

4.  Kinds  of  muscles?    The  voluntary?    Involuntary?    The  heart?    Give  the 
example.    The  hand  ?    Arm  ? 


THE   MUSCLES. 


5.  The  Tendons. — Tendons,  or  sinews,  are  the  ex- 
tremities of  muscles,  and  are  compactly  fastened  upon 
bone.  They  are  very  strong,  and  of  a  silvery  whiteness. 
They  may  be  felt  just  beneath  the  skin,  in  certain  parts  of 
the  body,  when  the  muscles  are  being  used,  as  at  the  bend 
of  the  elbow  or  knee.  The  largest  tendon  of  the  body  is 
that  which  is  inserted  into  the  heel,  called  the  tendon  of 
Achilles,  after  the  hero  of  the  Grecian  poet,  the  fable  relat- 
ing that  it  was  at  this  point  that  he  received  his  death- 
wound,  no  other  part  of  his  body  being  vulnerable.  The 
muscles  "which  extend  into  the  leg  unite  to  form  a  single 


FIG.  10. -VIEW  OF  KNEE-JOINT.    A.  Thigh  bone:  B,  Knee-pan  :  C,  D,  Leg  bones. 

and  very  powerful  tendon,  and  enclose  a  small  bone  called 
the  knee-pan,  which,  acting  like  a  pulley,  greatly  increases 
their  power,  and  at  the  same  time  protects  the  front  of  the 
knee-joint  (Fig.  10). 

6.  Muscular  Contraction. — The  muscles,  when  acted 
upon  by  the  appropriate  stimulus,  contract,  or  so  change 

5.  What  are  the  tendons  or  sinews?     Their  strength?     Color?    Location? 
Tendon  of  Achilles  ?    The  fable  ?    Muscles  of  the  leg  ? 

6.  Contraction  of  the  muscles  ?   Bending  of  the  arm  or  finger  ?    Other  agencies  ? 
Automatic  movements  ?    In  cold-blooded  animals  ? 


28  THE   MUSCLES. 


their  shape,  that  their  extremities  are  brought  nearer  to- 
gether. The  bending  of  the  arm,  or  of  a  finger,  is  effected 
in  this  manner,  by  the  will;  but  the  will  is  not  the  only 
means  of  producing  this  effect.  Electricity,  a  sharp  blow 
over  a  muscle,  and  other  stimuli,  also  cause  it.  Contrac- 
tion does  not  always  cease  with  life.  In  man  ,:.after  death 
from  cholera,  automatic  movements  of  hands  and  feet 
have  been  observed,  lasting  not  less  than  an  hour.  In 
certain  cold-blooded  animals,  as  the  turtle,  contraction 
has  been  known  to  take  place  for  several  days  after  the 
head  has  been  cut  off. 

7.  The  property  which,  in  muscle,  enables  these  move- 
ments to  take  place  is  called  contractility.    If  we  grasp  a 
muscle  while  in  exercise  (for  example,  the  large  muscle  in 
the  front  of  the  arm),  we  notice  the  alternate  swelling  and 
decrease  of  the  muscle,  as  we  move  the  forearm  to  and  fro. 
It  was  at  one  time  supposed  that  the  muscle  actually  in- 
creased in  volume  during  contraction.     This,  however,  is 
not  the  case ;  for  the  muscle,  while  gaining  in  thickness, 
loses  in  length  in  the  same  proportion;    and   thus,  the 
volume  remains  the  same  in  action  and  at  rest. 

8.  Contraction  is  not  the  permanent,  or  normal,  state 
of  a  muscle.     It  cannot  long  remain  contracted,  but  after 
a  shorter  or  longer  time,  it  wearies  and  is  obliged  to  relax. 
After  a  short  rest,  it  can  then  again  contract.     It  is  for 
this  reason  that  the  heart  can  beat  all  through  life,  night 
and  day,  by  having,  as  we  shall  hereafter  see,  a  brief  inter- 
val of  rest  between  successive  pulsations.    For  the  same 
reason,  it  is  more  fatiguing  to  stand  for  any  great  length  of 
time  in  one  position,  than  to  be  walking  the  same  period. 

9.  Relative   Strength  of  Animals.— The  amount 
of  muscular  power  which  different  animals  can  exert,  has 

7.  Contractility?     Give  the  illustration.    What  was  supposed?    What  is  the 
case? 

8.  What  further  in  relation  to  contraction  ?    Weariness  of  a  muscle  ?    Beating 
of  the  heart  ?    Standing  and  walking  ? 

9.  Muscular  power  of  animals  ?    How  tested  ?    Man's  power  ?   Worse's  ?    The 
comparison  ? 


THE   MUSCLES.  29 


been  tested  by  experiment.  By  determining  the  number 
of  pounds  which  an  animal  can  drag  upon  a  level  surface, 
and  afterward  comparing  that  with  its  own  weight,  we  can 
judge  of  its  muscular  force.  It  is  found  that  man  is  able 
to  drag  a  little  less  than  his  own  weight.  A  draught-horse 
can  exert  a  force  equal  to  about  two-thirds  of  his  weight. 
The  horse,  tnferefore,  though  vastly  heavier  than  man,  is 
relatively  not  so  powerful. 

10.  Insects  are  remarkable  for  their  power  of  carrying 
objects   larger  and  heavier  than   themselves.    Many  of 
them  can  drag  ten,  and  even  twenty  times  their  weight. 
Some  of  the  beetles  have  been  known  to  move  bodies  more 
than  forty  times  their  own  weight.     So  far,  therefore,  from 
it  being  a  fact  that  animals  have  strength  in  proportion 
to  their  weight  and  bulk,  the  reverse  of  that  statement 
seems  to  be  the  law. 

11.  Physical  Strength. — The  difference  in  strength, 
as  seen  in  different  individuals,  is  not  due  to  any  original 
difference  in  their  muscles.    Nature  gives  essentially  the 
same  kind  and  amount  of  muscles  to  each  person,  and  the 
power  of  one,  or  the  weakness  of  another,  arises,  in  great 
part,  from  the  manner  in  which  these  organs  are  used  or 
disused. 

12.  Many  authors  complain  of  the  physical  degeneracy 
of  men  at  the  present  day,  as  compared  with  past  genera- 
tions.    There  is  room  for  doubt  as  to  the  correctness  of 
this  statement.     Certain  experiments  have  recently  been 
made  with  the  metallic  armor  worn  seven  hundred  years 
ago,  by  which  it  is  found  that  any  man,  of  ordinary  height 
and  muscular  development,  can  carry  the  armor  and  wield 
the  weapons  of  an  age  supposed  to  be  greatly  our  superipr 
in  strength.    When  we  consider  that  in  those  days,  only 
very  strong  men  could  endure  the  hardships  of  soldier-life, 

1 0.  Power  of  insects  ?    Beetles  ?    Give  the  conclusion. 

11.  Difference  in  strength  of  individuals  ?    How  caused  ? 

12.  ComplailUMn  relation  to  degeneracy?    How  true?    How  determined  by 
armor  ?    The  fair  supposition  ? 


30  THE   MUSCLES. 


it  is  fair  to  suppose  that  our  age  has  not  so  greatly  degen- 
erated in  respect  to  physical  strength. 

13.  Importance  of  Exercise. — Action  is  the  law  of 
the  living  body.      Every  organ  demands  use  to  preserve 
it  in   full  vigor,  and  to  obtain  from  it  its  best  services. 
The  value  of  that   training  of  the  mind,  which  we  call 
education,  is  everywhere  recognized.     The  child  is  early 
put  to  school,  and  for  many  years  continues  to  study,  in 
order  that  his  brain,  which  is  the  great  centre  of  mental 
power,  may  act  healthfully  and  with  force.      It  is  impor- 
tant that  the  body,  also,  should  receive  its  education  by 
exercise.     This  is  especially  true  of  persons  belonging  to 
certain  classes  of  society,  whose  occupation  confines  them 
within  doors,  and  requires  chiefly  brain-work. 

14.  Persons  who  are  engaged  in  manual  labor  in  the 
open  air  obtain  all  the  exercise  necessary  for  bodily  health 
in  their  regular  business:  their  need  is  more  likely  to  be  a 
discipline  or  exercise  of  the  mind.     A  perfect  business  of 
life,  therefore,  would  be  one  which  would  combine  both 
physical  and  mental   labor  in  their  proper  proportions. 
If  such  a  business  were  possible  for  all  the  human  race,  life 
would  thereby  be  vastly  prolonged.    Such  is,  in  fact,  to  a 
large  extent,  the  occupation  pertaining  to  one  period  of 
life — childhood.     A  part  of  the  time  is  spent  by  the  child 
in  improving  his  mind  by  study,  and  another  part  of  the 
time  he  has  physical  exercise  in  his  games  and  sports. 

15.  The  Effects  of  Exercise. — Exercise  consists  in 
a  well-regulated   use   of  the  voluntary   muscular   system. 
The  effects,  however,  are  not  limited  to  the"  parts  used. 
Other  organs,  which   are   not  under  the   control   of  the 
will,    are  indirectly  influenced  by  it.    For  instance,  the 
heart  l*ats  more  rapidly,  the  skin  acts  more  freely,  and 


13.  Action?    Use  of  organs?     Training  of  the  mind?     The  child's  brain? 
Education  of  the  body  ?  • 

1 4.  Work  in  the  open  air  ?    A  perfect  business  ?    The  consequence  of  universal 
perfect  business  ?    Occupation  of  children  ? 

1 5.  In  what  does  exercise  consist  ?    Effects  of  it  ? 


THE   MUSCLES.  31 


becomes  hotter,  as  well  as  the  parts  beneath  it,  and  the  ap- 
petite and  power  of  digestion  are  increased.  An  increased 
exhalation  from  the  lungs  and  skin  purifies  the  current  of 
the  circulation,  and  the  body  as  a  whole  thrives  under  its 
influence. 

16.  The  immediate  effect  of  exercise,  however,  is  upon 
the  muscles  themselves;  for  by  use  they  become  firm  and 
large,  and  increase  in  power.    If  we  examine  a  muscle  thus 
improved  by  exercise,  we  find  that  its  fibres  have  become 
larger  and  more  closely  blended  together,  that  its  color  is 
of  a  darker  red,  and  that  the  supply  of  blood-vessels  has 
increased.      Without  exercise    the  muscle  appears  thin, 
flabby,  and  pale.     On  the-  other  hand,  excessive  exercise, 
without  sufficient   relaxation,   produces   in   the  muscle  a 
condition  not  very  different  from  that  which  follows  dis- 
use.   The  muscle  is  worn  out  faster  than  nature  builds  it 
up,  and  it  becomes  flabby,  pale,  and  weak. 

17.  Violent  exercise  is  not  beneficial;  and  spasmodic 
efforts  to  increase  the  muscular  strength  are  not  calculated 
to  secure  such  a  result.    Strength  is  the  result  of  a  gradual 
growth,  and  is  most  surely  acquired  if  the  exercise  be 
carried  to  a  point  short  of  fatigue,  and  after  an  adequate 
interval  of  rest.     To  gain  the  most  beneficial  results,  the 
exercise  should  be  at  regular  hours,  and  during  a  regular 
period.     The  activity  of  the  exercise,  and  the  time  de- 
voted to  it  must  vary,  of  course,  with  the  strength  of  the 
individual,  and  should  be  carefully  measured  by  it. 

18.  Different  Modes  of  Exercise. — There  are  very 
few  who  have  not  the  power  to  walk.    There  is  required 
for  it  no  expensive  apparatus,  nor  does  it  demand  a  period 
of  preliminary  training.     Walking  may  be  called  the  uni- 
versal exercise.    "With  certain  foreign  nations,  the  English 


16.  General  effect  upon  the  muscles?    Special  effect?    Effects  of  inaction? 
Of  excessive  exercise  ? 

17.  Of  violent  and  spasmodic  efforts?    Strength,  how  attained?    Give   the 
particulars. 

1 8 .  What  may  walking  be  called  ?    What  further  is  said  of  walking  ? 


32  THE   MUSCLES. 


especially,  it  is  a  very  popular  exercise,  and  is  practised 
habitually  by  almost  every  class  of  society ;  by  the  wealthy 
as  well  as  by  those  who  have  no  carriages;  by  women  as 
well  as  by  men. 

19.  Running,  leaping,  and  certain  other  more  rapid  and 
Violent   movements,  are   the   forms   of  exercise   that  are 
most  enjoyed  in  childhood.    For  the  child,  they  are  not 
too  severe,  but  they  may  be  so  prolonged  as  to  become 
injurious.      Instances  have  been  recorded  where  sudden 
death  has  resulted  after  violent  playing,  from  overtaxing 
the  heart:  for  example,  we  have  the  case  of  a  young  girl 
who,  while  skipping  the  rope,  and  endeavoring  to  excel 
her  playmates  by  jumping  the  greatest  number  of  times, 
fell  dead  from  rupture  of  the  heart. 

20.  Carriage-riding,  as  a  means  of  passive  exercise,  is  par- 
ticularly well  suited  to  invalids,  and  persons  advanced  in 
life.    Horseback  exercise  brings  into  use  a  greater  number 
of  muscles  than  any  other  one  exercise,  and  with  it  there 
is  an  exhilaration  of  feeling  which  refreshes  the  mind  at  the 
same  time.     It  is  one  of  the  manliest  of  exercises,  but  not 
less  suitable  for  women  than  for  men.    To  be  skilful  in 
riding,  it  is  best  to  begin  its  practice  in  youth ;  but  there 
are  very  few  kinds  of  exercise  of  which  the  same  is  not 
equally  true. 

21.  For  those  who  live  near  streams  or  bodies  of  water, 
there  are  the  delightful  recreations  of  boating,  swimming, 
and  skating.     Certain  of  these  exercises  have  a  practical 
importance  aside  from  and  above  their  use  in  increasing 
the  physical  vigor.     This  is  especially  true  of  boating  and 
swimming,  since  they  are  often  the  means  of  saving  life. 
Practice    in    these    exercises    also   teaches    self-reliance, 
courage,  and  presence  of  mind.     Persons  who  have  become 
proficient  in  these  vigorous  exercises  are  generally  the  ones. 

1 9.  What  is  paid  of  running,  and  other  like  movements  ?    What,  as  related  to 
childhood  ?    What  instance:*  are  a  I  hided  to  ?    Example  ? 

20.  Carriage-riding?    Horseback-riding? 

21.  Boating,  swimming,  and  skating  ? 


THE   MUSCLES.  33 


who,  in  times  of  danger,  are  the  quickest  to  act  and  the 
most  certain  to  do  so  with  judgment. 

22.  Physical  Culture.— That  form  of  exercise  which 
interests  and  excites  the  mind,  will  yield  the  best  results ; 
but  to  some  persons  no  kind  of  exertion  whatever  is,  at 
first,  agreeable.     They  should,  nevertheless,  make  a  trial 
of  some  exercise,  in    the  expectation  that,   as    they  be- 
come proficient  in  it,  it  will  become  more  pleasant.     In 
exercise,   as  many  sets  of  muscles  should  be  employed 
as  possible,  open-air    exercise    being   the    best.      Parlor 
gymnastics,  and    the    discipline  of  the  gymnasium   are 
desirable,  but  they  should  not  be  the  sole  reliance  for 
physical  culture.    No  in-door  exercise,  however  excellent 
in  itself,  can  fill  the  place  of  hearty  and  vigorous  activity 
in  the  open  air. 

23.  Gymnastic  Exercises  for  Schools  and  Col- 
leges.— In  the  system  of  education  among  the  ancients, 
physical  culture  predominated.     In  ancient  Greece,  physi- 
cal exercises  in-  schools  were  prescribed  and  regulated  by 
law,  and  hence  these  schools  were  called  gymnasia.     At 
the  present  time,  on  the  contrary,  this  culture  is  almost 
wholly  unknown,  as  a  part  of  the  course  of  education,  in 
our  schools  and  colleges.    In  a  few  of  our  institutions  of 
learning,   however,  physical    exercises   have  been   intro- 
duced, with  manifest  advantage  to  the  students,  and  they 
form  a  part  of  the  regular  curriculum  of  exercises, — as 
much   so  as  the  recitations  in  geography,  grammar,  or 
Greek.     The  good  effect  of  the  experiments,  as  shown  in 
improved  scholarship  as  well  as  increased  bodily  v^gor,  in 
the  institutions  where  the  plan  has  been  tried,  will,  it  is 
hoped,  lead  to  its  universal  adoption.     We  should  then 
hear  less  frequently  of  parents  being  obliged  to  withdraw 
their  children  from  school,  because  they  become  exhausted 

22.  What  kind  uf  exercise  yields  the  best  results  ?    What  advice  is  given  ? 

23.  Physical  culture  among  the  ancients  ?    In  Greece  ?    In  schools  and  college? 
at  the  present  time  ?    Result  to  the  body  and  mind  ? 

2* 


34  THE    MUSCLES. 


or,  perchance,  have  lost  their  health  from  intense  and  pro- 
tracted mental  application. 

24.  Were  gymnastics  more  common  in  our  educational 
institutions  we  should  not  so  often  witness  the  sad  spectacle 
of  young  men  and  women  leaving  our  colleges  and  semi- 
naries, with  finished  educations  it  may  be,  but  with  consti- 
tutions so  impaired,  that  the  life  which  should  be  devoted 
to  the  accomplishment  of  noble  purposes  must  be  spent  in 
search  of  health.     Spinal  curvatures,  which,  according  to 
the  experience  of  physicians,  are  now  extremely  frequent, 
especially  among  ladies,  would  give  place  to  the  steady 
gait  and  erect  carriage  which  God  designed  his   human 
creatures  should  maintain. 

25.  All  the  exercises  necessary  for  the  proper  develop- 
ment of  the  body  may  be  obtained  from  the  use  of  a  few 
simple  contrivances  that  every  one  can  have  at  home,  at 
little  cost — less  by  far  than  is  spent  for  useless  toys.    Many 
of  these  may  be  made  available  in  the  parlor  or  chamber, 
though  all  exercises  are  far  more  useful  in  the  open  air.    A 
small  portion  of  the  day  thus  spent  will  afford  agreeable 
recreation  as  well  as  useful  exercise.     The  Indian  club,  the 
wand,  the  ring,  and  the  dumb-bells  answer  ordinary  pur- 
poses very  well.     Illustrations  are  here  introduced  of  a  few 
simple  contrivances  that  may  be  useful  for  general  exer- 
cises,  and   are   specially   suitable   for  persons  with   weak 
spines ,  or  with  spines  that  are  the  subject  of  lateral  curva- 
ture. 

26.  One  of  the   simplest  appliances  for   strengthening 
the  muscles  of  the  spine,  designed  chiefly  to  exercise  the 
muscles  on  either  side  of  the  spine,  consists  of  two  wooden 
handles  attached  to  india-rubber  cords,  one  of  which  is 
attached  to  a  hook  made  fast  in  the  ceiling,  or  in  the  top 
of  the  door-case ;  and  the  other  to  another  hook  fastened 
in  the  wall,  door-post,  or  window-casing,  about  the  height 

24.  The  result  of  gymnastics  in  our  colleges  and  other  institutions  of  learning? 


THE   MUSCLES. 


of  the  shoulder.    When  traction  is  made  with  the  left  hand., 
it  exercises  the  muscles  on  the  left  side  of  the  spine,  while 


FIG.  11. 


those  on  the  opposite  side  are  left  almost  at  rest,  owing  to 
the  oblique  direction  given  to  the  shoulders  when  the  right 


PIG.  12. 


hand  grasps  the  horizontal  cord.     (This  appliance  will  be 
understood  by  referring  to  Fig.  13.) 


36 


THE   MUSCLES. 


27.  Fig.  11  shows  an  appliance  consisting  of  two  strong 
elastic  cords,  with  handles,  secured  to  a  hook  in  the  floor, 
so  arranged  that  the  patient  has  to  stoop  forward  to  reach 
them.  On  raising  the  body  the  spinal  muscles  are  power- 
fully exercised.  Fig.  12  shows  other  modes  of  using  the 
elastic  cords  for  strengthening  the  spine  and  chest. 


FIG.  13. 


28.  These  various  appliances  have  been  combined  so  as 
to  form  a  system  of  gymnastics  suitable  for  parlor  use; 
other  appliances  have  been  added  by  which  the  muscles  of 


THE   MUSCLES.  37 


the  legs  may  be  called  into  action  as  well  as  those  of  the 
spine  and  upper  part  of  the  body  (Fig.  13).  Combinations 
of  cords  suitable  for  particular  cases  may  also  be  made,  and 
by  using  one  or  several  cords  on  the  same  hook,  their  power 
may  be  adapted  to  the  strength  of  the  most  robust  as  well 
as  to  that  of  the  invalid,  or  of  the  most  delicate  child. 
The  entire  apparatus  is  quite  simple  in  its  construction 
and  inexpensive,  requiring  but  little  space,  and  at  the 
same  time  affording  a  great  variety  of  exercises. 

EXERCISES  THAT  MAY  BE   PRACTISED   o*r  THIS  APPA- 
RATUS. 

EXERCISE  I.  (Fig.  13). — Stand  erect  under  the  cords  and  place  the 
heels  together.  Grasp  the  handles  firmly,  keeping  the  knees  and 
elbows  stiff,  and  pull  downward  and  forward  until  the  fingers  nearly 
touch  the  toes.  Return  slowly  to  the  erect  position.  Repeat. 

EXERCISE  II.  (Fig.  13). — Stand  erect,  and  having  grasped  the 
handles  overhead  firmly,  separate  them  and  bring  them  down 
slowly  until  they  touch  the  sides :  then  return  them  slowly  to  the 
original  position.  Repeat. 

EXERCISE  III.  (Fig.  13). — Stand  erect,  heels  together,  grasp  the 
handles  overhead,  and  charge  forward  with  the  right  foot.  Return 
to  first  position,  and  then  charge  with  the  left.  Repeat,  using  the 
right  and  left  foot  alternately. 

EXERCISE  IV.  (Fig.  13). — Stand  erect,  heels  together.  Grasp  the 
handle  overhead,  and  charge  forward  with  the  right  foot,  knee  bent. 
Remain  in  this  position  and  bring  the  arms  down  to  the  sides  so  that 
the  arm  and  fore-arm  may  form  a  right  angle.  Still  holding  the 
handles,  thrust  forward,  first  the  right  hand  and  then  the  left,  until 
the  arm  is  straight.  Repeat.  Return  to  first  position,  then  charge 
forward  with  the  left  foot,  performing  the  same  movements  as  before. 

EXERCISE  V.  (Fig.  13). — In  this  exercise  we  change  to  the  pulleys 
leading  from  the  side  posts,  which  can  be  used  in  several  different 
ways.  1st.  Stand  erect,  heels  together,  facing  one  of  the  posts, 
grasp  the  handle  with  the  right  hand,  the  ajm  being  extended,  then 
flex  the  fore-arm  on  the  arm.  Repeat  Perform  the  same  move- 
ments with  the  left  hand.  2cl.  Stand  with  back  to  the  post ;  grasp 
the  pulley  behind  with  the  right  hand,  then  gradually  bring  the 
hand  forward  until  it  is  extended  in  a  straight  line  in  front.  Repeat. 
Perform  the  same  exercise  with  the  left  hand. 


THK 


VI.  vFis:.  l:M.  -This  exereise  is  espeeiallv  adapted  to  the 
Stirrups  are  so  arranged  that  they  can  bo  attaehed  to  the 
pulleys  overhead,  aiul  ean  han^r  down  to  within  three  or  tour  toot  of 
the  floor.  Place  the  foot  in  the  stirrup,  and  then  press  down  until  it 
touches  the  floor.  Repeat  Exercise  the  left  foot  in  the  same  way. 

EXERCISE  VIL  (Fig.  18V— This  exercise  requires  a  little  attention 
in  the  adjustment  of  the  apparatus.  Under  the  pulleys  in  the  floor 
aiv  passed  ropes  whidi  can  be  attached  to  the  snap-hooks  that  hold 
the  handles  overhead.  Stoop  forward  with  the  knees  stiff;  and  take 
hold  of  the  handles,  and  then  raise  the  body  to  the  erect  position. 
Repeat 

EXERCISE  Vin.  (Fig.  18).— Sit  on  the  floor  or  on  a  seat  three  or 
four  inches  high ;  bend  forward,  take  hold  of  the  handles,  and  per- 
form the  same  movements  that  you  would  in  rowing  a  boat 

EXERCISE  IX.  (Fig.  18).— The  trapeze  can  now  be  let  down ;  take 
hold  of  it  with  both  hands,  sustaining  the  weight  of  the  body  with 
the  arms,  then  rotate  the  body  first  from  right  to  left,  then  from  left 
to  right  alternately.  This  exercise  is  especially  suitable  for  females. 

F.XKKt-isK  X.  ^Kisr.  i;;\— <,;ra<p  the  trape/e  as  before,  bearing  all 
the  weight  with  the  arms :  then  draw  the  body  up  slowly  until  you 
can  place  the  chin  over  the  bars.  This  requires  strength  of  muscle, 
and  might  strain  if  done  too  violently ;  if  slowly  performed  there  is 
no  danger. 

These  are  but  a  few  of  the  exercises  that  can  be  practised  with 
this  apparatus.  As  these  become  familiar  they  can  easily  be  modi- 
fied, and  new  ones  can  be  arranged  to  meet  the  requirements  of 
particular  cases.  Host  of  the  exercises  described  can  be  practised 
with  one  hand  so  as  to  strengthen  the  muscles  on  one  side. 

29.  Rest. — We  cannot  always  be  active:  repose  must 
succeed  labor.  We  obtain  this  rest  partly  by  suspending 
all  exertion,  as  in  sleep,  and  partly  by  a  change  of  employ- 
ment It  is  said  that  Alfred  the  Great  recommended  that 
each  day  should  be  divided  in  the  following  manner: 
"Eight  hours  for  work,  eight  hours  for  recreation,  and 
eight  hours  for  sleep."  This  division  of  time  is  as  good  as 
any  that  could  now  be  made,  if  it  be  borne  in  mind  that, 
when  the  work  is  physical,  the  time  of  recreation  should 

aft.'Needof  tepoM?  How  do  tre  obtain  rat  ?  Alfred  the  Great !  The  ei«ht- 
hoor  diTfeion  of  UmoT 


THK    MI.'HCLKH. 


be  devoted  to  the  improvement  of  the  mind;  and  when 
mental,  we  should  then  recreate  by  means  of  physical 
exercise. 

30.  During  sleep,  all  voluntary  activity  ceases,  the  rapid- 
ity of  the  circulation  and  breathing  diminishes,  and  the 
temperature  of  the  body  falls  one  or  two  degrees.    In  con- 
sequence, the  body  needs  warmer  coverings  than  during 
the  hours  of  wakefulness.    During  sleep,  the  body  seems 
wholly  at  rest,  and  the  mind  is  also  inactive,  if  we  except 
those  involuntary  mental  wanderings  which  we  call  dreams* 
Nevertheless  a  very  active  and  important  physical  process 
is  going  on.    Nutrition,  or  the  nourishing  of  the  tissues, 
now  takes  place.    While  the  body  is  in  action,  the  process 
of  pulling  down  predominates,  but  in  sleep,  that  of  build- 
ing up  takes  place  more  actively.    In  this  way  we  are  re- 
freshed each  night,  and  prepared  for  the  work  and  pleasures 
of  another  day.    If  sleep  is  insufficient,  the  effects  are  seen 
in  the  lassitude  and  weakness  which  follow.    Wakefulness 
is  very  frequently  the  forerunner  of  insanity,  especially 
among  those  who  perform  excessive  mental  labor. 

31.  All  persons  do  not  require  the  same  amount  of  sleep, 
but  the  average  of  men  need  from  seven  to  nine  hours. 
There  are  well-authenticated  cases  where  individuals  have 
remained  without  sleep  for  many  days  without  apparent 
injury.    Frederick  the  Great  required  only  five  hours  of 
sleep  daily.    Bonaparte  could  pass  days  with  only  a  few 
hours  of  rest.    But  this  long  continued  absence  of  sleep  is 
attended  with  danger.    After  loss  of  sleep  for  a  long  period, 
in  some  instances,  stupor  has  come  on  so  profoundly,  that 
there  has  been  no  awaking. 

32.  There  are  instances  related  of  sailors  falling  asleep 

30.  Cessation  of  voluntary  activity  ?  Temperature  of  the  body  ?  Consequence  ? 
Body  and  mind  daring  sleep  ?    Nutrition  ?     Describe  it.    Consequence  of  inroffi- 
ci'rrj'  rten  -• 

31.  Amount  of  sleep  in  different  persons?    Cages?    Frederick  the  Great? 
Bonaparte?    Instance*  of  Jong  deprivation  of  sleep ? 

32.  Instance*  of  sailors  ?    French  soldiers  ?    During  torture  1 


40  THE   MUSCLES. 


on  the  gun-deck  of  their  ships  while  in  action.  On  the 
retreat  from  Moscow,  the  French  soldiers  would  fall  asleep 
on  the  march,  and  could  only  be  aroused  by  the  cry,  "The 
Cossacks  are  coming !"  Tortured  persons  are  said  to  have 
slept  upon  the  rack  in  the  intervals  of  their  torture.  In 
early  life,  while  engaged  in  a  laborious  country  practice, 
the  writer  not  unfrequently  slept  soundly  on  horseback. 
These  instances,  and  others,  show  the  imperative  demand 
which  nature  makes  for  rest  in  sleep. 


QUESTIONS  FOR  TOPICAL  REVIEW. 

PAGE 

1.  What  can  yon  state  of  the  number  and  division  of  the  muscles  ? 25,  26 

2.  Describe  the  structure  of  the  muscles 25,  26 

3.  Their  arrangement  in  pairs  and  consequent  action 2G 

4.  What  is  the  difference  between  the  motion  called  flexion  and  that  called 

extension  ? 26 

5.  Describe  their  action,  and  state  which  are  the  more  powerful 23 

6.  What  is  the  difference  between  voluntary  and  involuntary  muscles? 26 

7.  Illustrate  the  difference  between  the  two 20 

8.  State  all  you  can  of  the  tendons  or  sinews 27 

9.  What  is  meant  by  contraction  of  the  muscles  ? 27,  28 

10.  In  how  many  and  what  ways  may  contraction  be  effected  ? 28 

11.  What  is  stated  of  after-death  contraction  ? 23 

12.  Wrhy  cannot  a  muscle  in  life  continue  contracted  a  Ions:  time  ? 23 

13.  How  then  can  the  constant  beating  of  the  heart  be  explained  ? 28 

14.  How  docs  the  strength  of  a  man  compare  with  that  of  a  horse  ? 29 

15.  What  can  you  state  in  relation  to  the  relative  strength  of  animals  ?.   ...  28,  29 

16.  What,  in  relation  to  physical  strength  ? 29 

17.  What,  in  relation  to  physical  degeneracy  ? 29,  30 

18.  What,  in  relation  to  the  importance  of  exercise  ? 30 

19.  What  is  the  effect  of  exercise  upon  the  heart,  skin,  and  appetite  ?. 30,  31 

20.  How  docs  exercise  affect  the  current  of  the  body's  circulation  ? 31 

21 .  How  does  judicious  exercise  affect  the  muscles  ? , 31 

22.  What  is  stated  of  violent  and  spasmodic  exercise  ? 31 

23.  Of  the  exercise  of  walking  ? 31,  32,  33 

24  Of  running,  leaping,  and  other  modes  of  exercise  ? 3s 

25.  Of  physical  culture,  in  connection  with  out-door  exercises  ? 

26.  Of  the  importance  of  gymnastics  in  our  schools  and  colleges  ? 33,  34 

27.  Of  the  importance  of  rest  from  labor  or  exercise  ? •  •  •   -  38,  39 

28.  What  processes  take  place  during  sleep  ? » 

29.  What  effects  follow  insufficient  sleep  ? 39 


THE  INTEGUMENT,   OR   SKIN.  41 


CHAPTER  III. 
THE  INTEGUMENT,  OB  SKIN. 

The  Integument — Its  Structure — The  Nails  and  Hair — The  Complexion 
— The  Sebaceous  Glands — The  Perspiratory  Glands — Perspiration 
and  its  Uses — Importance  of  Bathing — Different  kinds  of  Baths — 
Manner  of  Bathing — The  Benefits  of  the  Sun — Importance  of  Warm 
Clothing — Poisonous  Cosmetics. 

1.  The  Integument. — The  skin  is  the  outer  covering 
of  the  body.    The  parts  directly  beneath  it  are  very  sensi- 
tive, and  require  protection.     This  is  shown  whenever  by 
accident  the  skin  is  broken,  pierced,  or  torn  off,  the  bared 
surface  being  very  tender,  and  painful  to  the  touch.   Nature 
has  provided  the  body  with  a  garment  that  is  soft,  pliable, 
close-fitting,  and  very  thin,  and  yet  sufficiently  strong  to 
enable  us  to  come  in  contact  with  the  objects  that  sur- 
round us,  without  inconvenience  or  suffering. 

2.  The  Structure  of  the  Skin. — When  examined  with 
the  aid  of  the  microscope,  the  skin  is  found  to  be  made  up 
of  two  layers — the  outer  and  the  inner.    The  inner  one  is 
called  the  cutis,  or  true  skin  ;   the  outer  one  is  the  epider- 
mis, or  scarf-skin.     The  latter  is  also  known  as  the  cuticle. 
These  two  layers  are  closely  united,  but  they  may  be  sepa- 
rated from  each  other.     This  separation  takes  place  when- 
ever, from  a  burn,  or  other  cause,  a  blister  is  formed; 
a  watery  fluid  is  poured  out  between  the  two  layers,  and 
lifts  the  epidermis  from  the  true  skin. 

Of  the  two  layers,  the  cuticle  is  the  thinner  in  most  parts 
of  the  body,  and  has  the  appearance  of  a  whitish  mem- 
brane. It  is  tough  and  elastic,  is  without  feeling,  and  does 


1 .  What  is  the  skin  ?     Parts  directly  beneath  ?    What  is  shown  ? 

2.  Microscopic  examination  ?     What  is  the  cutis  ?    The  cuticle  ?    Their  union  ? 
How  separated  ?    What  further  is  said  of  the  cuticle  ? 


42  THE   INTEGUMENT,   OR  SKIN. 

not  bleed,when  cut.  Examine  it  more  closely,  and  we  observe 
that  it  is  composed  of  minute  flat  cells,  closely  compacted, 
and  arranged  layer  upon  layer. 

3.  The  outer  layer  is  constantly  being  worn  out,  and 
falls  from  the  body  in  the  form  of  very  fine  scales.     It  is, 
also,  continually  forming  anew  on  the  surface  of  the  inner 
layer.     Its  thickness  varies  in  different  parts  of  the  body. 
Where  exposed  to  use,  it  is  thick,  hard,  and  horn-like,  as 
may  be  seen  on  the  soles  of  the  feet,  or  on  the  palms  of  the 
hands,  especially  of  those  who  are  accustomed  to  perform 
much  manual  labor.     This  is  an  admirable  provision  for 
the  increased  protection  of  the  sensitive  parts  below  the 
skin  against  all  extraordinary  exposure.     Even  the  liabil- 
ities of  these  parts  to  injury,  are  thus  kindly  provided  for 
by  "  the  Hand  that  made  us." 

4.  The  cutis,  or  true  skin,  lies  beneath  the  epidermis, 
and  is  its  origin  and  support.     It  is  firm,  dense,  elastic, 
very  sensitive,  and  is   freely  supplied  with  blood-vessels. 
It  is  closely  connected  with  the  tissues  below  it,  but  may 
be  separated  by  means  of  a  sharp  instrument.    The  surface 
of  the  cutis  is  not  smooth,  but  is  covered  here  and  there 
with  minute  elevations,  called  papillce.    These  are  arranged 
in  rows,  along  fine  lines,  or  ridges,  such  as  those  which 
mark  the  palm  and  fingers ;  their  number  is  about  80  to 
the   square   line  (a  line   being  one-tAvelfth   of  an  inch). 
These  papillce  contain  the  blood-vessels  which  carry  the 
supply  of  blood  needed  by  the  ever-wasting  skin.     They 
contain   nerves   also,   and   are  largely   concerned   in   the 
sense   of  touch;    hence   they   are   particularly   abundant 
where  the  touch  is  most  delicate,  as  at  the  ends  of  the 
fingers. 

5.  The  Nails  and  Hair, — These  are  appendages  of  the 

3.  Wearing  out  of  the  cuticle  ?    What  then  ?    Variety  in  thickness  of  cuticle  r 
How  accounted  for? 

4.  Location  and  office  of  the   cutis?    What  further  is  said  of  it?    Papillae? 
Touch  ? 

5.  What  are  the  nails  and  hair  ?    The  growth  of  the  nail  ?    The  rapidity  of  it3 
growth  2    Accident  to  the  nail  ? 


THE   INTEGUMENT,   OR   SKIN. 


43 


skin,  and  although  very  unlike  the  cuticle  as  it  appears  on 
the  surface  of  the  body,  they  are,  in  reality,  modified  forms 
of  that  layer  of  the  skin.  The  nail  grows  from  a  fold  of 
the  cuticle  at  the  root,  and  from  the  under  surface.  As 
fast  as  it  is  formed,  it  is 
constantly  being  pushed 
outward.  The  rapidity  of 
its  growth  can  be  ascer- 
tained by  filing  a  slight 
groove  on  its  surface,  and 
noticing  how  the  space  be- 
tween it  and  the  root  of 
the  nail  increases,  in  the 
course  of  a  few  weeks. 
When  the  nail  is  removed 
by  any  accident,  it  will  be 
replaced  by  a  new  one,  if 
the  root  be  not  injured. 

6.    The    hairs  are  pro- 
duced in  a  similar  manner ; 


5.  The  hair  sac. 
c.  TRANSVERSE  SECTION  OF  A  HAIR. 


Fig.  14. 

o,  b.    THE  ROOT  op  A  HAIR. 
the    Skm    forming    depreS-  i,2,3.  The  skin  forming  the  hair  sac.  4. 

sions,  or  hair  sacs,  from 
the  bottom  of  which  they 
grow  and  are  nourished  (Fig.  14).  They  are  found,  of 
greater  or  less  length,  on  almost  all  parts  of  the  surface, 
except  the  palms  of  the  hands  and  soles  of  the  feet.  On 
certain  parts  of  the  body,  they  grow  to  great  length ;  on 
other  parts  they  are  so  short,  that  they  do  not  rise  beyond 
the  hair  sac  in  which  they  originate. 

7.  The  bulb,  or  root,  from  which  the  hair  arises,  is 
lodged  in  a  small  pouch,  or  depression  in  the  skin.  The 
shaft  is  the  part  which  grows  out  beyond  the  level  of  the 
skin.  Its  growth  is  altogether  in  one  direction,  in  length 
alone.  The  outer  part  of  the  hair  is  quite  firm,  while  its 


6.  How  are  the  hairs  produced  ?    Difference  in  their  length  ? 

7.  Root  of  the  hair  ?    Shaft  ?    Firmness  and  softness  ofthe  hair? 


44  THE   INTEGUMENT,   OR  SKIN. 

interior  is  softer,  and  probably  conveys  the  fluids  by  which 
it  is  nourished.  The  hair  is  more  glossy  in  health  than  at 
other  times. 

8.  The  nail   serves  as  a  protection  to  the  end  of  the 
finger,  and  also  enables  us  to  grasp  more  firmly,  and  to 
pick  up  small  objects.     The  hair,  too,  is  a  protection  to 
the  parts  it  covers.     On  the  head,  it  shields  the  brain  from 
extremes  of  heat  and  cold,  and  moderates  the  force  of  blows 
upon  the  scalp.     On  the  body,  it  is  useful  in  affording  a 
more  extensive  surface  for  carrying  off  the  perspiration. 

9.  Complexion. — In   the  deeper  cells  of  the  cuticle 
lies  a  pigment,  or  coloring  matter,  consisting  of  minute 
colored  grains.    On  this  pigment  complexion  depends;  and, 
according  as  it  is  present  in  less  or  greater  amount,  occa- 
sions the  difference  of  hue,  that  exists  between  the  light 
and  dark  races  of  men,  and  between  the  blonde  and  bru- 
nette of  the  white  races.    Freckles  are  due  to  an  irregular 
increase  of  coloring  matter. 

10.  The  sun  has  a  powerful  influence  over  the  develop- 
ment of  this  pigment,  as  is  shown  by  the  swarthy  hue  of 
those  of  the  white  race  who  have  colonized  in  tropical 
climates.      It  is  also  well  illustrated  by  the  fact,  thai 
among  the  Jews  who  have   settled  in  northern  Europe, 
there  are  many  who  are  fair  complex ioned,  while  those 
residing  in  India,  are  as  dark  as  the  Hindoos  ground  them, 

11.  An  Albino  is  a  person  who  may  be  said  to  have  nc 
complexion:  that  is,  there  is  an  entire  absence  of  coloring 
matter  from  the  skin,  hair,  and  iris  of  the  eye.     This  con- 
dition more  frequently  occurs  among  the  dark  races,  and 
in  hot  climates,  although  it  has  been  observed  in  almosl 
every  race  and  clime. 

12.  Sebaceous  Glands. — There  are  in  the  skin  certain 

8.  Office  of  the  nail  ?    Of  the  hair?    Give  the  illustrations. 

9.  On  what  doe?  the  complexion  depend  ">.     Light  and  dark  races  ">.     Freckles  ! 

10.  Influence  of  the  sun  ?    How  illustrated?    Jews? 

11.  What  is  an  Albino?    Where  are  Albino*  found  ? 

l!4.  What  are  sebaceous  glands  ?    How  do  they  act?    Sebaceous  glands  of  th< 
fkce  ?    How  do  they  act  ? 


THE   INTEGUMENT,   OR   SKIN.  45 

small  glands,  which  produce  an  oily  substance,  called  se- 
baceous matter.  These  glands  are  little  rounded  sacs, 
usually  connected  with  the  hair-bulbs;  and  upon  these 
bulbs,  they  empty  their  product  of  oil,  which  acts  as  a, 
natural  and  adequate  dressing  for  the  hair  (4,  Fig.  13).  A 
portion  of  the  sebaceous  matter  passes  out  upon  the  sur- 
face, and  prevents  the  cuticle  from  becoming  dry  and  hard. 
The  glands  situated  upon  the  face  and  forehead,  open 
directly  upon  the  skin.  In  these,  the  sebaceous  matter  is 
liable  to  collect,  and  become  too  hard  to  flow  off  naturally. 

13.  These  glands  on  the  face  and  forehead  frequently 
appear,  on  the  faces  of  the  young,  as  small  black  points, 
which  are  incorrectly  called  "worms."     It  is  true,  that  oc- 
casionally living  animalcules  are  found  in  this  thickened 
sebaceous  matter,  but  they  can  only  be  detected  by  the  aid 
of  the  microscope.     This  sebaceous  matter  acts  not  only  to 
keep  the  skin  flexible,  and  furnish  for  the  hair  an  oily 
dressing,  but  it  especially  serves  to  protect  the  skin  and 
hair,  from  the  acridity  arising  from  the  perspiration. 

14.  The  Perspiratory  Glands. — The  chief  product 
of  the  skin's  action  is  the  perspiration.    For  the  forma- 
tion  of  this,  there   are   furnished   countless  numbers  of 
little  sweat-glands  in  the  true  skin.     They  consist  of  fine 
tubes,  with  globe-like  coils  at  their  deeper  extremity.   Their 
mouths  or  openings  may  be  seen  with  an  ordinary  magnifying 
glass,  upon  the  fine  ridges  which  mark  the  fingers.    These 
tubes,  if  uncoiled,  measure  about  one-tenth  of  an  inch  in 
length.     In  diameter,  they  are  about  one  three-hundredth 
of  an  inch,  and  upon  certain  parts  of  the  body  there  are  not 
far  from  three  thousand  of  these  glands  to  the  square  inch. 
Their  whole  number  in  the  body  is,  therefore,  very  great; 
and,  in  fact,  it  is  computed  if  they  were  all  united,  end  to  end. 
their  combined  measurement  would  exceed  three  miles. 

13.  Black  pointy  called  worms?    Animalcules?    Service  performed  by  seba- 
ceous matter? 

14.  Perspiration?    Sweat  stands?    Of  what  do  they  consist?    Dimension  of 
the  tubes? 


46  THE   INTEGUMENT,   OR  SKIN, 

15.  The  Sensible  and  Insensible  Perspiration.— 

The  pores  of  the  skin  are  constantly  exhaling  a  watery 
fluid;  but,  under  ordinary  circumstances,  there  is  no 
moisture  apparent  upon  the  surface,  for  it  evaporates  as 
rapidly  as  it  is  formed.  This  is  called  insensible  perspira- 
tion. Under  the  influence  of  heat  or  exercise,  however, 
this  fluid  is  excreted  more  abundantly,  and  appears  on  the 
surface  in  the  form  of  minute,  colorless  drops.  It  is  then 
termed  sensible  perspiration. 

16. .  Water  is  the  chief  component  of  this  fluid,  there 
being  about  ninety-eight  parts  of  water  to.  two  parts  of 
solid  matter.  The  quantity  escaping  from  the  body  varies 
greatly,  according  to  the  temperature  of  the  air,  the 
occupation  of  the  individual,  and  other  circumstances. 
The  average  daily  amount  of  this  excretion,  in  the  adult, 
is  not  far  from  thirty  ounces,  nearly  two  pints,  or  more 
than  nine  grains  each  minute. 

17.  The  Uses  of  the  Perspiration. — Besides  liber- 
ating from  the  blood  this  large  amount  of  water,  with  the 
effete  matter  it  contains,  the  perspiration  serves  to  regulate 
the  temperature  of  the  body.     That  is  to  say,  as  evapora- 
tion always  diminishes  temperature,  so  the  perspiration,  as 
it  passes  off  in  the  form  of  fine  vapor,  cools  the  surface. 
Accordingly,  in  hot  weather  this  function  is  much  more 
active,  and  the  cooling  influence  increases  in  proportion. 
When  the  air  is  already  charged  with  moisture,  and  does 
not  readily  receive  this  vapor  of  the  body,  the  heat  of 
the  atmosphere  apparently  increases,  and  the  discomfort 
therefrom  is  relatively  greater. 

18.  The  importance  of  this  excretion  is  shown  by  the 
effects  that  often  follow  its  temporary  interruption,  namely, 
headache,  fever,  and  the  other  symptoms  that  accompany 

1 5.  What  is  sensible  perspiration  ?    Insensible  perspiration  ? 

16.  Components   of  perspiration?    Upon   what  does   perspiration   depend? 
Amount  of  perspiration  daily  ? 

17.  What  does  perspiration  set  free  from  the  blood  ?    What  other  service  does 
perspiration  perform  ?    Explain  the  process. 

18.  Effect  of  interruption  of  excretion  ?    What  experiments  are  mentioned  ? 


THE   INTEGUMENT,   OR   SKIN.  47 

"taking  cold/'  When  the  perspiration  is  completely 
checked,  the  consequences  are  very  serious.  Experiments 
have  been  performed  upon  certain  smaller  animals,  as  rab- 
bits, to  ascertain  the  results  of  closing  the  perspiratory 
tubes.  When  they  are  covered  by  a  coating  of  varnish 
impervious  to  water  and  gases,  death  ensues  in  from  six  to 
twelve  hours ;  the  attendant  symptoms  resembling  those 
of  suffocation. 

19.  It  is  related  that,  at  the  coronation  of  one  of  the 
Popes  about  three  hundred  years  ago,  a  little  boy  was 
chosen  to  act  the  part  of  an  angel ;  and  in  order  that  his 
appearance  might  be  as  gorgeous  as  possible,  he  was  cov- 
ered from  head  to  foot  with  a  coating  of  gold  foil.    He  was 
soon  taken  sick,  and  although  every  known  means  were 
employed  for  his  recovery,  except  the  removal  of  his  fata! 
golden  covering,  he  died  in  a  few  hours. 

20.  The  Importance  of  Bathing. — From  these  con- 
siderations, it  is  evident  that  health  must  greatly  depend 
upon  the  free  action  of  the  skin.    "  He  who  keeps  the  skin 
ruddy  and  soft,  shuts  many  gates  against  disease."     When 
the  watery  portion  of  the  perspiration  evaporates,  the  solid 
matter  is  left  behind  on  the  surface.     There,  also,  remain 
the  scales  of  the  worn-out  cuticle,  and  the  excess  of  seba- 
ceous matter.     In  order  to  secure  the  natural  action  of  the 
skin,  these  impurities  require  to  be  removed  by  the  frequfcnt 
application  of  water. 

21.  In  warm  climates,  and  during  hot  weather,  ablution 
should   be  more  frequently   practised.     For   a  person   in 
good  health,  a  daily  cold  bath  is  advisable.     To  this  should 
be  added  occasionally  a  tepid  bath,  with  soap,  Avater  alone 
not  being  sufficient  to  remove  impurities  of  a  greasy  nature. 
Soap  facilitates  this,  by  forming  with  such  substances  a 
chemical  mixture,  which  is  readily  soluble  in  water,  and  is 
by  it  removed  from  the  body. 

19.  Give  the  story  in  relation  to  the  boy  covered  with  gold  foil. 

20.  Give  the  quotation.    Perspiration  ? 

2 1 .  Ablution  in  warm  climates  '-    What  advice  i?  iriven  * 


48  THE   INTEGUMENT,    OR   SKIN. 


22.  There  is  a  maxim  by  the  chemist  Liebig,  to  the  effect, 
that  the  civilization  of  a  nation  is  high,  in  proportion  to 
the  amount  of  soap  that  it  consumes ;  and  that  it  is  low,  in 
proportion  to  its  use  of  perfumes.     In  some  degree,  we  may 
apply  the  same  test  to  the  refinement  of  an  individual. 
The  soap  removes  impurity ;  the  perfume   covers,  while 
retaining  it. 

23.  The  different  kinds  of  Baths. — All  persons  are 
not  alike  able  to  use  the  cold  bath.    When  the  health  is 
vigorous,  and  the  system  does  not  feel  a  shock  after  such  a 
bath,  a  prompt  reaction  and  glow  upon  the  surface  will 
show  that  it  is  beneficial.    Where  this  pleasurable  feeling 
is  not  experienced,  but  rather  a  chill  and  sense  of  depres- 
sion ensues,  we  are  warned  that  the   system   will   not, 
with  impunity,  endure  cold  bathing. 

24.  It  should  also  be  borne  in  mind,  that  the  warm  or  hot 
bath  cannot  be  continued  so  long,  or  repeated  so  frequently 
as  the  cold,  on  account  of  the  enervating  effect  of  unusual 
heat  so  applied  to  the  body.     For  persons  who  are  not  in 
robust  health,  one  warm  bath  each  week  is  sufficient ;  this 
class  should  be  careful  to  avoid  every  extreme  in  reference 
to  bathing,  clothing,  and  whatever  greatly  affects  the  actioi! 
of  the  skin. 

25.  Sea-bathing  is  even  more  invigorating  than  fresh- 
water bathing.     Those  who  cannot  endure  the  fresh  water, 
are  often  benefited  by  the  salt-water  baths.     This  may  be 
accounted  for,  in  part,  by  the  stimulant  action  upon  the 
surface,  of  the  saline  particles  of  the  sea-water;  but  the 
exciting  scenes  and  circumstances  of  sea-bathing  also  exert 
an  important  influence.    The  open-air  exercise,  the  rolling 
surf,  the  genial  weather,  and  usually  the  cheerful  company, 
add  to  its  intrinsic  benefits. 


22.  Liebig'p  maxim  ?    What  further  in  added  ? 

23.  What'is  said  about  cold  bathinir  ? 

24.  What  Is  Mid  about  warm  bathing? 

25.  What  is  said  about  sea-bathing ? 


THE    INTEGUMENT,    OR    SKIN.  49 

26.  Time  and  Manner  of  Bathing. — A  person  in 
sound  health  may  take  a  bath  at  almost  any  time,  except 
directly  after  a  full  meal.     The  most  appropriate  time  is 
about  three  hours  after  a  meal,  the  noon-hour  being  proba- 
bly the  best.     For  the  cold  bath,  taken  rapidly,  no  time  is 
better  than  immediately  after  rising.     Those  beginning  the 
use  of  cold  baths  should  first  try  them  at  70°  Fahr.,  and 
gradually  use  those  of  a  lower  temperature.    From  five  to 
twenty  minutes  may  be  considered  the  proper  limit  of  time 
to  remain  in  a  bath ;  but  a  sensation  of  chilliness  is  a  signal 
to  withdraw  instantly,  whether  at  home,  or  at  the  sea-side. 
Two  sea-baths  may  be  taken  daily ;  one  of  any  other  kind 
is  sufficient. 

27.  The  body  should  be  warm,  rather  than  cold,  whei) 
stepping  into  the  bath;  and  after  it,  the  skin  should  be 
thoroughly  dried  with  a  coarse  towel.   It  is  best  to  continue 
friction  until  there  is  a  sensation  of  warmth  or  "glow" 
throughout  the  entire  surface.     This  reaction  is  the  test 
of  the  good  effects  of  the  bath.     If  reaction  is  still  incom- 
plete, a  short  walk  may  be  taken,  especially  in  the  sunshine. 
It  is  very  congenial,  however,  both  to  health  and  comfort, 
to  rest  for  a  short  time  directly  after  bathing,  or  to  take 
some  light  refreshment.     This  is  better  than  severe  exer- 
cise or  a  full  meal. 

28.  Bathing  among   the  Ancients. — The   Romans 
and   other   nations   of  antiquity    made   great  use  of  the 
vapor-bath  as  a  means  of  preserving  the  health,  but  more 
particularly  as  a  luxury.     Their  method  was  not  unlike 
that  employed  in   northern  Europe  at   the   present  day. 
The  public  baths  of  Rome  and  other  cities  are  among  the 
grandest    and    most    interesting   monuments   of    ancient 
luxury  and  splendor;  and  from  their  ruins  have  been  re- 
covered some  of  the  most  beautiful  works  of  art. 


26.  What  is  gaid  as  to  the  time  and  manner  of  bathing  ? 

27.  Condition  of  the  body  when  bathing?    Direction,  after  bathing? 

28.  Bathing  among  the  ancients?    Bath?  of  Rome? 

3 


50  THE    INTEGUMENT,    OR    SKIN. 

29.  The   Thermae,   as   the   baths  of  Rome  were  called, 
were  of  great  extent,  built  very  substantially,  and  orna- 
mented at  vast  expense.     They  were  practically  free  to  all, 
the  cost  of  a  bath   having   been  less  than  a  cent.     It  is 
related  that  some  persons  bathed  seven  times  a  day.    After 
the  bath  their  bodies  were  anointed  with  perfumed  oil.     If 
the  weather  was  fine,  they  passed  directly  from  the  Thermae 
into  the  gymnasium,  and  engaged  in  some  gentle  exercise 
previous  to  taking  the  midday  meal.     Between  two  and 
three  in  the  afternoon  was  the  favorite  hour  for  this  ancient 
luxury.     Swimming  was  a  favorite  exercise,  and  a  knowl- 
edge of  it  was  regarded  as  necessary  to  every  educated  man. 
Their  common  expression,  when  speaking  of  an  ignorant 
person,  was,  "  He  can  neither  read  nor  swim." 

30.  The  Sun-Bath. — Some  also  were  accustomed  daily 
to  anoint  themselves,  and  lie  or  walk  in  apartments  ar- 
ranged for  the  purpose,  with  naked  bodies  exposed  to  the 
direct  rays  of  the  sun.     There  is  an  interesting  allusion  to 
this  practice,  in  a  letter  of  the  younger  Pliny  to  the  his- 
torian Tacitus,  describing  the  destruction  of  Pompeii  by 
an  eruption  of  Vesuvius.     "  My  uncle,"  (Pliny  the  elder,) 
"was  at  that  time  in  command  of  the  fleet  at  Misenum. 
On  the  24th  of  August,  about  one  in  the  afternoon,  my 
mother  desired  him  to  notice  a  cloud  which  seemed  6f  un- 
usual shape  and  dimensions.     He  had  just  returned  from 
talcing  the  benefit  of  the  sun,  and  after  a  cold  bath,  and  a 
slight  repast,  had  retired  to  his  study."     Then  follows  a 
description  of  the  destruction  of  Pompeii,  and  the  death 
of  the  elder  Pliny. 

31.  We  may  judge  somewhat  of  "the  benefits  of  the 
sun,"  by  observing  the  unnatural  and  undeveloped  condi- 
tion of  plants  and  animals  which  are  deprived  of  light. 
Plants  become  blanched  and  tender ;  the  fish  of  subterra- 


29.  After  the  bath  ?    Swimming  among  the  ancients  * 

30.  The  Sun-bath  ?    The  story  of  Pliny  ? 

3 1 .  Benefit  of  the  pun  ?    Eftx-et  upon  plants  *    Skin  ? 


THE    INTEGUMENT,    OR   SKIN.  51 

nean  lakes,  where  no  light  enters,  are  undersized,  and  have 
no  eyes;  tadpoles  kept  in  the  dark  do  not  develop  into 
frogs;  men  growing  up  in  mines  are  sallow,  pale,  and 
deformed.  Besides  the  well-known  effect  of  solar  light  in 
tanning  the  skin,  it  also  makes  it  thicker  and  better  able 
to  resist  exposure;  though  the  complexion  may  be  thereby 
injured,  the  health  gains  more  than  compensates  for  the 
loss  of  beauty.  "To  make  good  the  loss  of  the  lily,  where 
the  sun  has  cast  his  ray,  he  seldom  fails  to  plant  the  rose." 

32.  Clothing. — In   reference   to   clothing,  we   are   far 
more  apt,  in  our  changeful  climate,  to  use  too  little  than 
too  much.     An  aphorism  of  Boerhaave,  worth  remember- 
ing, if  not  of  adopting,  is,  "We  should  put  off  our  winter 
clothing  on  midsummer's  day,  and  put  it  on  again  the  day 
after."     He  also  says,  "Only  fools  and  beggars  suffer  from 
the  cold ;  the  latter  not  being  able  to  get  sufficient  clothes, 
the  others  not  having  the  sense  to  wear  them."     The  prac- 
tice of  exposing  the  limbs  and  necks  of  young  children, 
for  the  alleged   purpose  of  "hardening"   them,  is  quite 
hazardous.     It  is  not  to  be  denied  that  some  seem  to  be 
made  tough  by  the  process ;  but  it  is  so  only  with  the  rugged 
children,  the  delicate  ones  will  invariably  suffer  under  this 
fanciful  treatment.     As  has  been  stated  before,  the  skin  is 
constantly  acting,  by  night  as  well  as  by  day.     It  is  there- 
fore conducive  both  to  cleanliness  and  comfort  to  change 
entirely  the  clothing  on  retiring  for  the  night.     The  day- 
clothing  should  be  aired  during  the  night,  and  the  bedding 
should  be  aired  in  the  morning,  for  the  same  reason. 

33.  Poisonous    Cosmetics. — The    extensive    use   of 
cosmetics  for  the  complexion  is  a  fertile  source  of  disease. 
The  majority  of  these  preparations  contain  certain  poison- 
ous   mineral    substances,   chiefly    lead.     Now,    the   skin 
rapidly  absorbs  the  fine  particles  of  lead,  and  the  system 


32.  Direction  about  clothing?    Exposing  limbs  of  children  ?    Clothing,  night 
and  day  ? 

33.  Cosmetics  ?    Painters'  colic  ? 


52  THE    IXTEGUMEXT,    OR   SKIX. 

experiences  the  same  evil  effects  that  are  observed  among 
the  operatives  in  lead  works  and  painters,  namely,  "paint- 
ers' colic,"  and  paralysis  of  the  hands,  called  "  wrist-drop." 
34.  Certain  hair-dyes  also  contain  lead,  together  with 
other  noxious  and  filthy  ingredients.  These  do  not  work 
as  great  harm  as  the  cosmetics,  since  they  are  purposely 
kept  away  from  the  skin,  but  they  rob  the  hair  of  its 
vitality.  Eye-washes,  too,  are  made  from  solutions  of  lead, 
and  many  an  eye  has  been  ruined  by  their  use.  They  de- 
posit a  white  metallic  scale  on  the  surface  of  the  eye,  which 
becomes  a  permanent  obstruction  to  the  vision. 


QUESTIONS  FOR  TOPICAL  REVIEW. 

PAGE 

1.  What  are  the  characteristics  of  the  skin,  and  what  office  does  it  perform  ?       41 

2.  What  can  you  state  of  the  structure  of  the  skin  ? 41 

3.  Describe  the  cuticle  aiid  tell  its  use 41, 42 

4.-  Describe  the  cutis  or  true  skin  and  tell  its  use 42 

5.  What  can  you  state  of  the  nature  and  growth  of  the  nail  ? 42, 43 

6.  Of  the  nature  and  growth  of  the  hair  ? 4:2,  43,  4 1 

7.  Of  the  offices  performed  by  the  nails  and  hair  * 44 

8.  How  is  the  difference  in  complexion  in  different  persons  accounted  for  ?.        44 

9.  How  is  the  presence  of  freckles  accounted  for  ? 44 

10.  How  does  Nature  provide  a  dressing  for  the  hair  ? 44,  45 

11.  What  other  service  do  the  sebaceous  glands  perform  ? 45 

12.  State  what  you  can  of  the  perspiratory  gland* 45 

1H.  What  is  the  difference  between  sensible  and  insensible  perspiration  ? . . .        46 

14.  State  the  uses  and  importance  of  perspiration 46, 47 

15.  What  impurities  gather  naturally  on  the  skin  ? 47 

16.  Repeat  what  is  said  of  the  importance  of  bathing 47, 48 

17.  When  should  we  indulge  in  cold,  warm,  and  sea  bathing  ? 48,  49 

18.  What  is  the  effect  in  each  case  ? 48 

1H.  What  directions  are  given  as  to  the  time  and  manner  for  bathing  ? 49 

20.  What  is  related  of  bathing  among  the  ancients  ? 49,  50 

21.  What,  is  related  to  show  the  antiquity  of  snn-bathing  ? 50 

22.  What  are  the  effects  of  snn-bathing  ? -rA  51 

23.  What  directions  are  given  in  relation  to  clothing  the  body  ? , 51 

24.  What  can  you  state  of  poisonous  cosmetics  ? 51,52 

25.  Of  hair-dyes  and  eye-washes? 52 


THE    CHEMISTRY    OF    FOOD.  53 


CHAPTER  IV. 
THE  CHEMISTRY  OF  FOOD. 

The  Source  of  Food — Inorganic  Substances —  Water — Salt — Lime — Iron 
— Organic  Substances — Albumen,  Fibrin,  and  Casein — The  Fats  or 
Oils — The  Sugars,  Starch,  and  Gum — Stimulating  Substances — 
Necessity  of  a  Regulated  Diet. 

1.  The  Source  of  Food. — The  term,  food  includes  all 
those  substances,  whether  liquid  or  solid,  which  are  neces- 
~ary  for  the  nourishment  of  the  body.     The  original  source 
of  all  food  is  the  earth,  which  the  poet  has  fitly  styled  the 
"  Mother  of  all  living."    In  her  bosom,  and  in  the  atmos- 
phere about  her,  are  contained  all  the  elements  on  which 
life  depends.     But  man  is  unable  to  obtain  nourishment 
directly  from  such  crude  chemical  forms  as  he  finds  in  the 
inorganic  world.     They  must,  with  a  few  exceptions,  be 
prepared  for  his  use,  by  being  transformed  into  new  and 
higher  combinations,  more  closely  resembling  the  tissues 
of  his  own  body. 

2.  This  transformation  is  effected,  first,  by  the  vegetable 
world.     But  all  plants  are  not  alike  useful  to  man ;  while 
some  are  absolutely  hurtful.     Accordingly,  he  must  learn 
to  discriminate  between  that  which  is  poisonous  and  that 
which  is  life-supporting.     Again,  all  parts  of  the  same 
plant  or  tree  are  not  alike  beneficial:  in  some,  the  fruit, 
in  others,  the  leaves,  and  in  others,  the   seeds    only  are 
'sufficiently   refined    for  his   use.     These    he   must    learn 
to  select ;  he  must  also  learn  the  proper  modes  of  prepar' 
ing  each  kind  for  his  table,  whether  by  cooking  or  othe 
processes. 


1 .  The  term  food  ?    Source  of  food  ?    Need  of  preparing:  food  ? 

2.  Usefulness  and  hurtfulness  of  plants  ?    What  then  must  man  do  ?     Parti?  of 
the  same  plant  or  tree  ? 


54  THE    CHEMISTRY    OF   FOOD. 

3.  Again,  certain  forms  of  the  vegetable  creation  which 
are  unfit,  in  their  crude  state,  for  man's  food,  and  which  he 
rejects,  are  chosen  as  food  by  some  of  the  lower  animals, 
and  are,  by  them,  made  ready  for  his  use.     Thus  the  bee 
takes  the  clover,  that  man  cannot  eat,  and  from  it  collects 
honey.     The  cattle  eat  the  husks  of  corn  and  the  dried 
grass,  that  are  by  far  too  coarse  for  man,  and  in  their  own 
flesh  convert  them  into  tissues  closely  resembling  his  mus- 
cular tissue.     In  this  way,  by  the  aid  of  the  transforming 
processes  of  the  vegetable  and  animal  creations,  the  simple 
chemical  elements  of  the  mineral  kingdom  are  elaborated 
into  our  choice  articles  of  food. 

4.  Tnorganic  Substances. — The  substances  we  use  as 
food  are  classified  as  organic  and  inorganic.     By  organic 
substances  are  meant  those  derived  from  living  forms,  such 
as  vegetables  and  animals.     Inorganic  substances  are  those 
simpler   inanimate   forms  which   belong  to   the   mineral 
kingdom.     The  former  alone  are  commonly  spoken  of  as 
food,  but  the  latter  enter  very  largely  into  the  constitution 
of  the  body,  and  must  therefore  be  present  in  our  food. 
With  the  exception  of  two  articles,  water  and  common 
salt,  these  substances  only  enter  the  system  when  blended 
with  organic  substances. 

5.  Water. — Water,  from  a  physiological  point  of  view,  is 
the  most  important  of  all  the  articles  of  food.     It  is  every- 
where found  in  the  body,  even  in  the  bones  and  the  teeth. 
It  has  been  computed  that  as  large  a  proportion  as  two- 
thirds  of  the  body  is  water.     The  teeth,  the  densest  of  the 
solids  in  the  human  system,  contain  ten  per  cent,  of  water. 
The  muscles,  tendons,  and  ligaments  are  more  than  half 
water;  for  it  is  found  that  they  lose  more  than  half  their 


3.  Certain  forms  of  vegetable  creation?    Example  of  the  bee?    Cattle?    The 
inference  ? 

4.  What   classification  ?     Define    organic    substances.      Inorganic.     Organic, 
how  spoken  of?    The  inorganic  ?    Water  and  salt  ? 

5.  Water  in  physiology  ?"'  Where  found  ?    Computation?   Water  in  the  teeth? 
Muscles,  tendons,  and  ligaments  ?    How  ascertained?    Water  in  the  fluids  of  the 
body  ?    What  is  the  advantage  ? 


THE    CHEMISTRY    OF    FOOD.  55 

weight  when  dried  with  moderate  heat.  But  it  is  in  the 
fluids  of  the  body  that  water  is  found  most  abundantly. 
It  gives  to  them  the  power  of  holding  a  great  variety  of 
substances  in  solution,  and  is  the  great  highway  by  which 
new  supplies  are  conveyed  to  the  point  where  they  are 
required,  and  by  which  old  particles  of  matter,  that  have 
served  their  uses,  are  brought  to  the  outlets  of  the  body  to 
te  thus  removed  from  the  system. 

C.  Man  can  remain  a  longer  time  without  solid  food 
than  without  water.-  He  may  be  deprived  of  the  former 
for  ten  to  twelve  hours  without  great  suffering,  but  depri- 
vation of  water  for  the  same  length  of  time  will  produce 
both  severe  pain  and  great  weakness.  The  food  should  contain 
not  less  than  two  parts  of  water  to  one  of  solid  nutriment. 
Water  constitutes  the  great  bulk  of  all  our  drinks,  and  is 
also  a  large  constituent  of  the  meats,  vegetables,  and  fruits 
which  come  upon  the  table.  Fruits,  especially,  contain  it 
in  great  abundance,  and,  in  their  proper  season,  furnish 
most  agreeable  and  refreshing  supplies  of  the  needed  fluid. 

7.  Common   Salt. — Salt,   or  sodium   chloride,   as   an 
article  of  food,  is  obtained  chiefly  from  the  mineral  king- 
dom; although  plants  contain  it  in  small  quantities,  and 
it  is  also  found  in  the  tissues  of  nearly  all  animals  used 
as  food.     In  the  human  body,  it  is  an  ingredient   of  all 
the  solids  and  fluids.     The  importance  of  salt  to  animal 
life  in  general,  is  shown  by  the  great  appetite  for  it  mani- 
fested by  domestic  animals,  and  also  by  the  habitual  resort 
of  herds  of  wild  beasts  to  the  "  salt-licks"  or  springs.     In 
those  parts  of  the  world  where  salt  is  obtained  with  diffi- 
culty, man  places  a  very  high  price  upon  it. 

8.  Experiments  upon   domestic  animals  show  that  the 
withdrawal  of  salt  from  their  food,  not  only  makes  their 


6.  Length  of  time  man  can  do  without  food  or  water  ?    Give  the  comparison  ? 
Bulk  of  drinks  ?    Constituent,  of  meats?,  etc.  ?     Fruits  ? 

7.  Salt,  how  obtained  ?     Where  found?    In  the  human  body?     Importance  oi 
^alt  ?    What  else  can  yon  st ato  of  the  value  of  salt  ? 

8.  Experiments  upon  animals? 


55  IHE  CHEMISTRY  OF  FOOD. 


hides  rough  and  causes  the  hair  to  fall  out,  but  also  inter- 
feres  with  the  proper  digestion  of  food.  If  it  be  withheld 
persistently,  they  become  entirely  unable  to  appropriate 
nourishment,  and  die  of  starvation. 

9.  Salt  is  usually  taken  into  the   system  in   sufficient 
quantities  in  our  food.     Even  the  water  we  drink  often 
has  traces  of  it.     The  habitual  use  of  much  salt  in  cook- 
ing, or  as  a  seasoning  at  the  table,  is  not  wise;  and  while 
it  may  not  lead  to  consumption,  as  some  writers  declare,  it 
is  a  bad  habit  in  itself,  and  leads  to  the  desire  for  other  and 
more  injurious  condiments. 

10.  Lime. — This  is  the  mineral  substance  which  we 
have  spoken  of  before  as  entering  very  largely  into  the  com- 
position of  the  bones.     It  is  the  important  element  which 
gives   solidity  and  permanence   to  the   framework   upon 
which  the  body  is  built.     Calcium  tri-phosphate,  or  "  bone- 
earth,"  is  the  chief  ingredient  of  the  bones  and  teeth,  but 
is  found  in  the  cartilages  and  other  parts  of  the  body  in 
smaller  quantities. 

11.  How  does  this  substance  find  its  way  into  the  body? 
Meat,  milk,  and  other  articles  obtained  from  the  animal 
kingdom  contain  it,  and  it  is  abundantly  stored  away  also 
in  the  grains  from  which  our  bread  is  made,  in  wheat,  rye, 
and  Indian  corn.     In  early  life,  while  the  body  is  growing, 
the  supplies  of  this  substance  should  be  carefully  provided. 
The  evil  effects  of  the  deprivation  of  it  are  too  often  and 
painfully  evident  in  the  softening  of  the  bones,  and  in  the 
predisposition  to  curvature  of  the  spine — deformities  which 
are  most  deplorable  and  which  continue  through  life. 

12.  Iron. — This  substance  is  probably  the  most  abun- 
dant and  widely  diffused  of  the  metals.     It  is  found  in 


9.  Salt,  how  taken  into  the  system  ?    Its  use  in  cooking  ?    Consumption  ? 

10.  Lime  in  the  bones?    What  does  it  impart  ?    Chief  ingredient  ot  the  bones 
and  teeth  ?    Where  else  found  ? 

11.  How  does  lime  find  its  way  into  the  body?    Early  life?    Effect  of  its 
deprivation  ? 

12.  Iron,  its  abundance  and  diffusion  ?    Where  found  ?    What  part  of  the  blood 
is  it  ?    How  supplied  to  the  system  ?     In  case  of  loss  of  blood  or  wasting  disease  ? 


THE   CHEMISTRY    OF    FOOD.  57 


most  of  the  vegetables,  and  is  a  very  important  component 
of  animal  tissues.  It  enters  into  the  composition  of  hu- 
man blood  in  about  one  part  per  thousand.  Ordinarily, 
the  food  conveys  to  the  system  enough  iron  for  its  use,  but 
it  must  sometimes  be  introduced  separately  as  a  remedy, 
especially  after  great  loss  of  blood,  or  after  some  wasting 
disease.  Under  its  influence  the  blood  seems  to  be 
rapidly  restored,  and  a  natural  color  of  the  lips  and  skin 
replaces  the  pallor  caused  by  disease. 

13.  Other  Inorganic  Substances. — In  addition  to 
the  substances  mentioned,  the  mineral  kingdom  supplies 
compounds  of  soda,  potash,  and  magnesia,  which  are  es- 
sential for  the  use  of  the  body.  They  occur  in  small 
quantities  in  the  body,  and  enter  it  in  combination  with 
the  various  articles  of  diet. 

14.  Organic  Substances. — These  substances  are  derived 
from  the  vegetable  and  animal  creations.  They  comprise 
all  those  articles  which  are  commonly  spoken  of  as  "  food," 
and  which  are  essential  to  sustain  the  body  in  life  and 
strength.  They  are  divided  into  three  groups,  namely: 
the  Albuminoid  substances,  the  Fats,  and  Sugars. 

15.  The  Albuminoids. — This  class  includes  three  im- 
portant nutritive  substances — (1)  Albumen,  which  gives  it 
its  name;  (2)  Fibrin,  including  gluten;  and  (3)  Casein. 
These  compounds  constitute  a  large  part  of  the  human 
body,  and  the  food  contains  them  in  proportionally  large 
quantities.  Their  importance  is  so  great,  and  the  system 
so  promptly  suffers  from  their  absence,  that  they  have  been 
styled  the  "  nutritious  substances."  The  properties  which 
they  hold  in  common  are,  that  they  do  not  crystallize,  and 
have  a  jelly-like  form,  except  when  heat  is  applied  to  them, 
when  they  harden,  or  coagulate. 


1  3.  Soda,  potash,  and  magnesia  ?    How  do  they  occur  ? 

1  \.  Onranic  eubstances,  whence  derived  ?    What  do  they  comprise  ?    Groups  :. 
li.  The  Albuminoid  class,   includes   what?      These    compounds    conatituta 
what?      The  food '?    Their  importance?    Their  properties  ? 

3* 


58  THE    CHEMISTRY    OF   FOOD. 


16.  They  likewise  decompose,  or  putrefy,  under  the  influ- 
ence of  warmth  and  moisture.     Hence  the  decay  of  all 
dead  animal  tissues.     Cold  arrests  this  process.     It  is  well 
known  that  milk,  eggs,  and  the  like,  "  keep"  much  longer 
in  winter  than  at  other  seasons.     The  bodies  of  elephants, 
caught  in  the  ice  many  hundred  years  ago,  are  occasion- 
ally borne  by  the  icebergs  to   the  coast  of  Siberia,  com- 
pletely frozen,  but  preserved  almost  perfectly  in  form  and 
limb. 

17.  Albumen  exists  in  milk,  meat,  the  grains,  and  the 
juices  of  many  plants;  but  the  purest  form  is  obtained 
from  the  white  of  egg.     When  we  consider  that  an  egg  is 
composed  chiefly  of  albumen  and  water — namely,  six  parts 
in  seven;  and  when  we  also  consider  the  numerous,  diverse, 
and  complex  tissues — the  muscles,  bones,  internal  organs, 
bill,  claws,  and  feathers — with  which  the  chick  is  equipped 
on  leaving  his  shell,  we  are  impressed  with  the  importance 
of  these  apparently  simple  constituents  of  the  food  and 
body. 

18.  Fibrin  is   derived  from  meats,  and  exists  in  the 
blood  both  of  man  and  the  lower  animals.     Gluten,  or 
vegetable  fibrin,  resembles  closely  true  fibrin,  and  is  abun- 
dantly furnished  in  wheat  and  other  grains  from  which 
flour  is  commonly  made.     Animal  fibrin  coagulates  spon- 
taneously when  it  is  removed  from  the  body,   and  thus 
causes  the  "clotting"  of  the  blood. 

19.  Casein  is  the  curdy  ingredient  of  milk,  and  a  highly 
important  food-substance.     Its  coagulation  in  milk  takes 
place  not  from  heat,  but  by  the  addition  of  an  acid,  and 
also  when  milk  becomes  sour  from  exposure  to  the  air.    It 
is  commonly  effected,  however,  by  introducing  a  piece  of 
rennet,  a  preparation  made  from  a  calf's  stomach.     The 
curds,  or  casein,  may  then  be  separated  from  the  wliey, 

1 6.  Decomposition  ?    Effect  of  cold  ?    Illustrations  ?    Elephants  ? 

17.  In  what  substance!*  does  albumen  exist  ?    What  further  is  said  of  the  e<*s * 

18.  Fibrin,  gluten,  clotting  of  the  blood  ? 

19.  Casein  ?    Its  coagulation  ?     Effect  of  rennet  ?    Making  of  cheese? 


THE   CHEMISTRY    OF    FOOJ).  50 

and  made  into  cheese,  by  pressing  it  sufficiently  to  drive 
off  the  water. 

20.  The  Fats  or  Oils. — This  is  the  second  group  of 
organic  foods.    Those  which  are  more  solid  are  called  fats  : 
the  more  fluid  ones  are  the  oils.     Oleaginous  substances 
are  supplied  in  both  animal  and  vegetable  food;  but,  from 
whatever  source  derived,  they  are  chemically  much  alike. 
They  are  insoluble  in  water,  and  yet  they  unite  readily 
with  the  watery  fluids  of  the  body,  and  are  by  them  con- 
veyed to  its  various  parts  for  their  nourishment.     This  is 
due  to  their  property  of  "emulsifying;"  that  is, they  are 
held  in  suspension,  in  a  finely  divided  state,  in  water.     Or- 
dinary milk  is  an  example  of  an  emulsion.     We  know  that 
it  contains  fat ;  for  butter  is  obtained  from  it,  and,  under 
the  microscope,  the  minute  oil-globules  may  be  distinctly 
seen. 

21.  In   our   country   and   climate,    and   also   in   colder 
climates,  fatty  articles  of  food  are  principally  derived  from 
the  animal  creation,  such  as  meat  or  flesh,  milk  and  butter. 
But  most  of  the  bread-stuffs  contain  more  or  less  fat  or  oil; 
Indian  meal  as  much  as  nine  parts  in  a  hundred. 

22.  Among  persons  living  in  cold  climates,  the  appetite 
for  oleaginous  food  is  especially  eager ;  and  they  require 
large  quantities  of  it  to  enable  them  to  resist  the  depress- 
ing  influences  of  cold.     Since   vegetation   is  scanty  and 
innutritions,  and  the  waters  of  the  frozen  regions  abound 
in  animal  life,  they  must  rely  wholly  upon  a  diet  derived 
from  the  latter  source.     The  Esquimaux  consumes  daily 
from  ten  to  fifteen  pounds  of  meat  or  blubber,  a,  large 
proportion   of  which  is   fat.     The   Laplander  will  drink 
train-oil,  and  regards  tallow-candles  as  a  great  delicacy. 
In  hot  climates,  on  the  contrary,  where  flourish  the  olive 


20.  What  are  the  fata  ?    The  oils  ?    How  supplied?    How  alike?    Emulsifying? 
Example  *    How  do  we  know  it? 

21.  Whence  are  fatty  articles  of  food  derived? 

22.  Appetite  of  persons  in  cold  climates  ?    What  do  they  require  ?    Upon  what 
must  they  rely  ?    Why?    The  Esquimaux?     Laplander?      Olive  and  palm  ? 


60  THE    CHEMISTKY    OF    FOOD. 

and  the  palm,  this  kind   of  food  may  be  obtained  from 
vegetable  sources  in  abundant  quantities. 

23.  The  Sugars,  or  the  Saccharine  Substances. — 
These  constitute  the  third,  and  last,  group  of  the  organic 
substances,  which  are  employed  as  food.  This  group  em- 
braces, in  addition  to  the  different  kinds  of  Sugar,  the 
varieties  of  starch  and  gum,  from  whatever  source  derived. 
The  two  substances  last  named  do  not,  at  first  sight,  pre- 
sent many  points  of  similarity  to  sugar ;  but  they  closely 
resemble  it  in  respect  to  their  ultimate  chemical  composi- 
tion, being  made  up  of  the  same  elements,  in  nearly  the 
same  proportions.  And  their  office  in  the  system  is  the 
same,  since  they  are  all  changed  into  sugar  by  the  processes 
of  digestion. 

*  24.  Sugar  is  chiefly  of  vegetable  origin;  the  animal 
varieties  being  obtained  from  honey  and  milk.  The  most 
noticeable  characteristic  of  this  substance  is  its  agreeable, 
sweet  taste,  which  makes  it  everywhere  a  favorite  article  of 
food.  But  this  quality  of  sweetness  is  not  possessed  by  all 
the  varieties  of  sugar  in  the  same  degree ;  that  obtained 
from  milk,  for  instance,  has  a  comparatively  feeble  taste, 
but  rather  imparts  a  gritty  feeling  to  the  tongue.  The 
other  important  properties  of  sugar  are,  its  power  to 
crystallize  when  evaporated  from  watery  solutions,  such  as 
the  juices  of  many  plants ;  a  tendency  to  ferment,  by  which 
process  alcohol  is  produced;  and  a  ready  solubility  in 
water.  This  latter  quality  renders  it  very  easy  of  digestion, 
and  more  so  than  any  other  of  the  saccharine,  group.  It  is 
computed  that  the  annual  production  of  sugar,  in  all  parts 
of  the  world,  is  more  than  one  million  of  tons.  The  kind 
of  sugar  that  is  in  ordinary  use,  in  this  country,  is  prepared 
from  the  juice  of  the  sugar-cane,  which  contains  eighteen 
per  cent,  of  sugar.  In  France  it  is  manufactured  from  the 

23.  Which  are  the  third  of  the  organic  groups?    What  do  they  embrace? 
Points  of  resemblance  ? 

24.  Origin  of  the  sugars?    Ordinary  eugar?    Beetroot?    Maple-sugar?    Grape- 
r-ugar?    Cane-sugar? 


THE    CHEMISTRY    OF    FOOD. 


Gi 


beet  root,  which  holds  about  nine  per  cent. ;  the  maple- tree 
of  our  climate  yields  a  similar  sugar.  The  sweet  taste  of 
fruits  is  due  to  the  presence  of  grape-sugar:  the  white 
grains  seen  on  raisins  belong  to  this  variety.  Cane-sugar 
is  more  soluble  than  the  latter,  and  has  twice  the  sweeteu- 
;ng  power. 

25.  Starch. — This  is  the  most  widely  distributed  of 
the  vegetable  principles. 
It  is  tasteless,  inodorous, 
and  does  not  crystallize. 
It  consists  of  minute 
rounded  granules,  which, 
under  the  microscope, 
reveal  a  somewhat  uni- 
form structure  (Fig.  15). 
Starch  will  not  dissolve 
in  cold  water,  but  in 
boiling  water  the  small 
grains  burst  open,  and 
may  then  be  dissolved 
and  digested. 

26.  The  bread  stuffs,   wheat,  corn,  and   rye  flours,  are 
more  than  one-half  starch.     Rice,  which  is  the  "staff  of 
life"  to  one-third  of  the  human  family,  contains  eighty 
per   cent.      Unripe   fruits    have   much    starch   in   them, 
which  renders  them  indigestible  when    eaten  uncooked; 
for  the  grains  of  raw  starch  are  but  slightly  acted  upon 
within  the  body.     But,  under  the  potent  chemistry  of  the 
sun's  ray,  this  crude   material   is   converted   into   sugar. 
Thus   are   the   fruits  prepared  by  the   careful    hand    of 
Nature,  so  that  when  ripe  they  may  be  freely  used  without 
further  preparation. 

27.  Gum  is  commonly  found  in   those  articles  which 

25.  Starch,  how  widely  distributed?    Its  qualities?    Its  constituents?    Its 
solubility  ? 

26.  How  much  starch  in  bread-stuffs  ?    In  rice  ?    Unrine  fruits?    Ripe  fruits? 

27.  Gum,  where  found  ?    Its  composition  ?     Gum  Arabic-  ? 


FIG.  15.— GRANULES  OF  POTATO  STAHCH. 


62  THE   CHEMISTRY    OF   FOOD. 

also  contain  starch ;  and  has  the  same  chemical  composi- 
tion as  the  latter,  but  is  much  less  nutritious.  In  the 
East,  gum-arabic  and  similar  substances  are  largely  em- 
ployed as  food.  Persons  who  travel  by  caravan  across  vast, 
sandy  deserts,  find  such  substances  well  adapted  to  their 
wants,  since  they  are  not  perishable,  and  are  easily  packed 
and  carried. 

28.  Stimulating  Substances. — The  three  classes  of 
food-principles  already  considered — the  Albuminoids,  the 
Fats,  and  the  Sugars — comprise  all  the  more  important 
organic  ingredients  of  our  food.      There   are,  besides,    a 
great  variety  of  coloring  and  flavoring  matters  that  stim- 
ulate or  increase  the  appetite  for  food  by  appealing   to  the 
eye  and  taste;  but  they  are  not  nutritious,  and  are  quickly 
separated  from  the   truly  useful   substances,  and  do  not 
long  remain  in  the  body.     Among  these  may  be  classed 
spices,  flavors  of  fruits,  tea,  coffee,  and  vegetable  acids. 

29.  Necessity  of  a  Regulated  Diet.— A  great  vari- 
ety of  experiments  have  been  tried  in  order  to  test  the  rela- 
tive value  of  the  different  nutritive  principles.     They  have 
been  practised  to  some  extent  upon  man,  but  chiefly  upon 
those  inferior  animals  which  require  a  similar  diet  to  man. 

30.  By  this  means  it  has  been  demonstrated  that — first, 
when  any  one  of  these  substances  is  eaten  exclusively,  the 
body  is  imperfectly  nourished,  and  life  is  shortened.     Dogs 
fed  exclusively  upon  either  albumen,  fat,  or  sugar,  soon  die 
of  starvation.     Second,  a  diet  long  deprived   of  either   of 
these  principles,  is  a  fertile  cause  of  disease;  for  example, 
on  ship-board,  where  fresh  vegetables  are  not  dealt  out  for  a 
long  period,  scurvy  becomes  prevalent  among  the  sailors. 
They  are,  however,  to  a  certain  extent  mutually  convertible, 
and  thus  the  missing  article  is  indirectly  supplied.     For 

28.  The  three  classes  of  food  principles  ?     What  besides?     What  is  ?aid  of 
them  ?    Name  the  articles  not  nutritions. 

29.  What  is  said  of  experiments  that  have  been  tried  ? 

30.  What  has  been  demonstrated  in  the  first  place?    Example?     Second  de- 
monstration ?    Example  ?    Give  the  illustration  in  relation  to  convertibility. 


THE   CHEMISTEY   OF   FOOD.  63 

instance,  sugar  changes  to  fat  in  the  body;  and  hence,  as 
is  well  known,  the  "  hands"  on  a  sugar  plantation  grow 
fat  during  the  sugar  season,  by  partaking  freely  of  the 
ripened  juices  of  the  cane. 

31.  That  is  the  best  diet  therefore  which  contains  some 
of  each  of  these  principles,  in  due  proportion;  and  that  is 
the  worst  which  excludes  the  most  of  them.  The  cravings 
and  experience  of  man  had  unerringly  guided  him  to  a 
correct  regulation  of  his  diet,  long  before  the  chemistry 
of  food  was  understood;  so  that  his  ordinary  meals 
long  ago  combined  these  various  principles,  the  necessity 
and  value  of  which  are  now  explained. 


QUESTIONS  FOR  TOPICAL  REVIEW. 

PAGE 

1.  What  is  understood  by  the  term  food  ? 53 

2.  What  can  yon  state  in  relation  to  the  source  of  food  ? 53 

3.  What  discriminations  and  selections  are  necessary  ? 53,  54 

4.  How  can  you  tell  the  organic  from  the  inorganic  substances  51 54 

5.  What  relative  position  does  water  hold  as  an  article  of  food  ? 54 

6.  In  what  parts  of  the  body  is  water  found  ? 54,  55 

7.  In  what  articles  that  we  eat  is  it  found  ? 55 

8.  If  you  were  required  to  go  without  water  or  solid  food  for  a  number  of  days, 

which  would  you  prefer  to  have,  and  why  ? 55 

9.  What  can  you  state  of  the  importance  of  salt  as  an  article  of  food  ? 55,  56 

10.  How  abundant  is  salt,  and  how  does  it  find  its  way  into  the  human  sys- 

tem ? 55,  56 

11.  What  can  you  state  of  the  importance  of  lime  in  the  body  ? 56 

12.  What,  of  the  importance  of  iron  ? 56,  57 

13.  What  furthor  ie  stated  of  other  inorganic  substances  ? 57 

14.  What  in  relation  to  organic  substances  ? 57 

15.  What  can  you  state  in  relation  to  the  albuminoids  ? 57,  58 

16.  What,  in  relation  to  albumen  ? ^ 

17.  What,  in  relation  to  casein  ? ^  59 

18.  In  relation  to  the  fats  or  oils,  and  how  generally  consumed  ? 59,  60 

19.  What  do  we  understand  by  the  sugars  or  saccharine  substances  ? 60 

20.  State  what  yon  can  of  fmsrar— its  origin  and  various  qualities fiO-  fit 

21 .  Of  starch— its  varieties  and  qualities • 61 

22.  Of  the  abundance  of  starch,  and  its  importance  as  a  food  principle 61 

23.  What  is  stated  In  relation  to  stimulating  substances  ? 62 

24.  Of  the  necessity  for  regulation  in  diet? 62,  63 


64  FOOD    AND    DRINK. 


CHAPTER  V. 
FOOD     AND     DRINK. 

Necessity  for  Food — Waste  and  Repair — Hunger  and  Thirst — Amount 
of  Food — Renovation  of  ike  Body — Mixed  Diet — Milk — Eggs — Meat 
—Cooking— Vegetable  Food— Bread— Tfie  Potato— Fruits— Purity 
of  Water — Action  of  Water  upon  Lead — Coffee,  Tea,  and  Clwcolate 
—Effects  of  AlcoJwl. 

1.  Necessity  for  Food. — Activity  is  everywhere  fol- 
lowed by  waste.     The  engine  uses  up  coal  and  water  to 
produce   motion,  the   stream   wears  away  its   bank,   the 
growing  corn-blade  draws  tribute  from  the  soil.   When  the 
human  body  acts,  and  it  is  always  in  action  during  life,  some 
of  its  particles  are  worn  out  and  thrown  off.     This  waste 
must  constantly  be  repaired,  or  the  body  suffers.     In  this 
fact  is  seen  the  necessity  for  food.     The  particles,  thus  worn 
out,  being  henceforth  useless,  are  removed  from  the  body. 
Our  food  and  drink  are  rapidly  transformed  into  a  new 
supply  of  living,  useful  material,  to  be  in  turn  used  up 
and  replaced  by  a  fresher  supply. 

2.  Waste  and  Repair. — In   this   way  the   healthful 
body,  though  always  wasting,  is  always  building  up,  and 
does  not  greatly  change  in  size,  form,  or  weight.     At  two 
periods  of  life  the  processes  of  waste  and  repair  are  not  ex- 
actly balanced.     In  early  life  the  process  of  building  up  is 
more  active,  and  in  consequence  the  form  is  plump,  and 
the  stature  increases.     Repair  now  exceeds  waste.     On  the 
other  hand,  when  old  age  comes  on,  the  wasting  process  is 
more  active,  the  flesh  and  weight  diminish,  the  skin  falls 
in  wrinkles,  and  the  senses  become  dull.     Only  during  the 
prime  of  life — from  about  twenty  to  sixty  years  of  age — is 
the  balance  exact  between  loss  and  gain. 


1 .  What  follows  activity  ?    Examples  ?    Necessity  for  food  ? 

2.  Give  the  theory  in  relation  to  waste  and  repair. 


FOOD    AND    DRINK.  65 


3.  Hunger  and  Thirst. — When  the  system  is  deprived 
of  its  supply  of  solid  food  during  a  longer  time  than  usual, 
nature   gives   warning   by    the    sensation    of    hunger,    to 
repair  the  losses  that  have  taken  place?    This  sensation 
or  pain  appears  to  be  located  in  the  stomach,  but  it  is  really 
a  distress  of  the  system  at  large.     Let  a  sufficient  quantity 
of  nourishment  be  introduced  into  the  system  in  any  other 
way  than  by  the  mouth,  and  it  will  appease  hunger  just  as 
certainly  as  when  taken  in  the  usual  manner. 

4.  The  feeling  of  thirst,  in  like  manner,  is  evidence  that 
the   system   is   suffering   from   the  want   of  water.     The 
apparent  seat  of  the  distress  of  thirst  is  in  the  throat ;  but 
the  injection   of  water  into  the  blood-vessels  is  found  to 
quench  thirst,  and  by  the  immersion  of  the  body  in  water, 
the  skin  will  absorb  sufficient  to  satisfy  the  demands  of  the 
system.     The  length  of  time  that  man  can  exist  without 
food  or  drink  is  estimated  to  be  about  seven  days.    If  water 
alone  be  supplied,  life  will  last  much  longer ;  there  being 
cases  recorded  where  men  have  lived  twenty  days  and  over, 
without  taking  any  solid  food. 

5.  Quantity  of  Food. — The  quantity  of  food  required 
varies  greatly,  according  to  the  individual  and  his  mode  of 
life.     The  young,  and  others  who  lead  active  lives,  or  who 
live  in  the  open  air,  require  more  food  than  the  old,  the 
inactive,  or  the  sedentary.     Those  who  live  in  cold  regions 
require  more  than  the  inhabitants  of  hot  climates.     Habit, 
also,  has  much  to  do  with  the  quantity  of  food  required. 
Some  habitually  eat  and  drink  more   than  they  actually 
need,  while  a  few  eat  less  than  they  should. 

6.  The  average  daily  quantity  of  food  and  drink  for  a 
healthy  man  of  active  habits  is  estimated  at  six  pounds. 
This  amount  may  be  divided  in  about  the  following  pro- 

3.  System  deprived  of  food?    Warning?    What  is  the  pain  ?    How  proved  ? 

4.  Feeling  of  thirst?    Seat  of  the  pani  ?    How  proved?    Time  a  person  can 
exist,  without  food  ? 

5.  Amount  of  food  required?     The  young  and  others?    Those  living  in   hot 
and  cold  climates  ?     Habits  * 

6.  Quantity  of  food  daily  ?    How  divided  ?   Compare  with  the  weight  of  t  lie  body  ? 


66  FOOD    AND    DRINK. 


portions:  the  mineral  kingdom  furnishes  three  and  one- 
half  pounds,  including  water  and  salt;  the  vegetable  king- 
dom, one  and  one-half  pounds,  including  bread,  vegetables, 
and  fruits;  the  animal  kingdom,  one  pound,  comprising 
meat,  eggs,  butter,  and  the  like.  This  quantity  is  about 
one  twenty-fourth  the  weight  of  the  body,  as  it  is  generally 
computed ;  the  average  weight  of  an  adult  man  being  placed 
at  140  pounds.  A  man,  therefore,  consumes  an  amount  of 
solid  and  liquid  nutriment  every  twenty-four  days  equal 
in  weight  to  that  of  his  body,  a  corresponding  amount 
being  excreted,  or  removed  from  the  system  in  the  same 
time. 

7.  Renovation  of  the  Body.— By  this  process,  so  far 
as  weight  is  concerned,  the  body  might  be  renewed  every 
twenty-four  days;  but  these  pounds  of  food  are  not  all  real 
nutriment.     A  considerable  portion  of  that  which  we  eat 
is  innutritions,  and  though  useful  in  various  ways,  is  not 
destined  to  repair  the  losses  of  the  system.     An  opinion 
has  prevailed  that  the  body  is  renewed  throughout  once  in 
seven   years ;   how  correct  this   may  be  it  is  not  easy  to 
decide,  but  probably   the   renovation   of  the   body  takes 
place  in  a   much   shorter  period.     Some  parts   are  very 
frequently  renewed,  the  nutritive  fluids  changing  more  or 
less  completely,  several  times  during  the  day.    The  muscles, 
and  other  parts  in  frequent  exercise,  change  often  during  a 
year ;  the  bones  not  so  often,  and  the  enamel  of  the  teeth 
probably  never  changes  after  being  once  fully  formed. 

8.  Mixed  Diet. — The  habits  of  different  nations  in 
respect  to  diet  exhibit  the  widest  and  strangest  diversity. 
The  civilized,  cook   their  food,  while   savages  often    eat 
it  in  a  raw  state.     Some  prefer  it  when  fresh,  others  allow 
it   to   remain   until   it  has    become   tainted   with   decay. 
Those  dwelling  in  the  far  north  subsist  almost  wholly  on 

-  7.  How  often  then  might  the  body  be  renewed?    Why  is  it  not?    Opinion? 
How  correct  ?     What  further  is  stated  ? 
8.  Habits  of  nations?    Give  the  different  cases. 


FOOD    AND    DRINK.  67 

animal  food,  while  those  living  in  hot  climates  have  boun- 
tiful supplies  of  delicious  fruits  with  which  to  satisfy  all 
their  bodily  wants.  One  race  subsists  upon  the  banana, 
another  upon  the  blubber  of  seals.  In  temperate  climates, 
a  diet  composed  partly  of  vegetable  and  partly  of  animal 
food  is  preferred. 

9.  The  important  point  to  consider  is,  however,  not  one 
of  origin,  but  whether  the  chemical  principles  (mentioned 
in  the  last  chapter)  enter  into  the  composition  of  the  diet. 
A  purely  vegetable  diet  may  be  selected  which  would  contain 
all  the  principles  necessary  to  sustain  life.   It  is  recorded  of 
Louis  Cornaro,  a  Venetian  noble,  that  he  supported  himself 
comfortably  for  fifty-eight  years  on  a  daily  allowance  of 
twelve  ounces  of  vegetable  food,  and  about  a  pint  of  light 
wine.     On  the  other  hand,  the  food  of  John  the  Baptist, 
consisting  of  "locusts  and  wild  honey/'  is  an  example  of 
the  sustaining  power  of  a  diet  chiefly  animal  in  its  origin. 

10.  In  our  climate,  those  who  lead  active  lives  crave  an 
allowance  of  animal  food;  and  it  has  been  found  by  ex- 
perience that  with  it  they  can  accomplish  more  work  and 
are  less  subject  to  fatigue,  than  without  it.     Among  na- 
tions where  an  exclusively  vegetable  diet  is  employed,  indi- 
gestion is  a  disorder  especially  prevalent. 

11.  The  necessity  for  occasionally  changing  or  varying 
the  diet,  is  seen  in  the  fact  that  no  single  article  comprises 
all  the  necessary  principles  of  food,  and  that  the  contin- 
uous use  of  any  one  diet,  whether  salt  or  fresh,  is  followed 
by  defective  nutrition  and  disease.     There  is  one  exception 
to    this   rule  :    in    infancy,  milk  alone  is  best  calculated 
to  support  life ;  for  then  the  digestive  powers  are  incom- 
pletely developed,  and  the  food  must  be  presented  in  the 
simplest   form   possible.     It   should   also  be   remembered 


9.  The  point  to  consider?    Vegetable  diet?    Louis  Cornaro  ?     John  the  Bap 
tist  ? 

1 0.  What  has  been  found  in  our  climate  ?    Exclusive  vegetable  diet  ? 

11.  Necessity  for  change  in  diet?    Continuous  use  of  the  same  diet?     Excep 
tion  ?    Why  ?    Too  rich  diet  ?    Horses  ? 


08  FOOD    AXI)    DRINK. 


that  too  rich  diet  is  injurious,  just  as  truly  as  one  that  i« 
inadequate.  When  the  food  of  horses  is  too  nutritious,  in- 
stinct leads  them  to  gnaw  the  wood-work  of  their  mangers. 

12.  Different  Articles  of  Diet— Milk.— Milk   is 
the  earliest  nutriment  of  the  human  race,  and  in  the  selec- 
tion and  arrangement  of  its  constituents,  may  be  regarded 
as  a  model  food,  no  other  single  article  being  capable  of 
sustaining  life  so  long.     Cow's  milk  holds  casein,  one  of 
the  albuminoids,  about  five  parts  in  one  hundred;  a  fatty 
principle,  when    separated,  known   as   butter,  about   four 
parts;  sugar  of  milk  four  parts;  water  and  salts  eighty- 
seven  parts.     The  casein  and  fatty  substance  are  far  more 
digestible  in  milk,  than  after  they  have  been   separated 
from  it  in  the  form  of  cheese  and  butter. 

13.  Since  milk,  in  itself,  is  so  rich  an  article  of  food, 
the  use  of  it  as  a  beverage  is  unwise,  unless  the  quantity 
of  the  other  articles   consumed  be   reduced  at  the  same 
time.     The  milk  sold  in  cities  is  apt  to  be  diluted  with 
water.    The  way   to  detect  the  cheat  is  by  testing  the 
specific  gravity  of  the  article.     Good  milk  is  about  1030; 
ckimmed  milk  1035;  but  milk  diluted  one-fifth  is  1024. 
An   instrument  called    the  lactometer  is  also   used,    by 
which  the  amount  of  cream  present  is  ascertained. 

14.  Eggs. — The  egg  is  about  two-thirds  water,  the  bal- 
ance is  pure  albumen  and  fat  in  nearly  equal  proportions. 
The  fat  is  in  the  yolk,  and  gives  it  its  yellow  color,     l^gg-s 
contain  none  of  the  sugar-principles,  and  should  be  eaten 
with  bread  or  vegetables  that  contain  them.     Soft-boiled 
eggs  are  more  wholesome  than  those  which  are  hard-boiled 
or  fried,  as  the  latter  require  longer  time  to  digest. 

15.  Meats. — The  meats,  so  called,  are  derived  from  the 
muscular  parts  of  various   animals.     They  are  most  im- 


1  2.  Milk  as  a  model  food  ?    Cow's  milk  ?    The  constituents  when  separated  y 
1  3.  Milk  as  a  beverage  ?    Milk  sold  in  cities  ?     How  to  detect  the  cheat  ? 
14.  Composition  of  eggs?    Yolk?     How  should  eggs  be  eaten  ?     Why?    How 
t-oiled  ?     Why  ? 
1  5.  Meats,  whence  derived  ?     Why  important  ?     Fk-h  of  youuir  animal-  y 


FOOD    AND   DRINK.  69 


portant  articles  of  food  for  adults,  inasmuch  as  they  are 
richly  stored  with  albuminoid  substances,  and  contain 
more  or  less  fat.  Such  food  is  very  nourishing  and  easily 
digested  if  eaten  when  fresh, — veal  and  pork  being  excep- 
tions. The  flesh  of  young  animals  is  more  tender  and,  in 
general,  more  digestible  than  that  of  older  ones.  All  meat 
is  more  tough  immediately  after  the  killing  of  the  animal, 
but  improves  by  being  kept  a  certain  length  of  time. 

16.  Some  persons  prefer  flesh  that  has  begun  to  show 
signs   of  decomposition,  or  is  unmistakably  putrid.     By 
some,  venison  is  not  considered  to  have  its  proper  flavor 
until  it  is  tainted.      In  England,  people  prefer   mutton 
that  is  in  a  similar  condition,  just  as  on  the  continent  of 
Europe  many  delight  in  cheese  that  is  in  a  state  of  decom- 
position.   In  certain  less  civilized  countries  flesh  is  riot  only 
eaten  uncooked,  but  in  a  mouldy,  rotten  condition.     The 
use  of  such  food  is  not  always  immediately  injurious,  but 
it  predisposes  to  certain  diseases,  as  indigestion  and  fevers. 

17.  Cold  is  one  means  of  preserving  meat  from  decay. 
In  the  markets  of  northern  Russia,  the  frozen  carcases  of 
animals  stand  exposed  for  sale  in  the  winter  air  for  a  con- 
siderable time,  and  are  sawn  in  pieces,  like  sticks  of  wood, 
as  the  purchases  are  made;      such  meat,  when  thawed, 
being  entirely  fit  for  food.     Beef  and  pork  are  preserved 
by  salting  down  in  brine,  and  in  this  condition  may  be 
carried  on  long  voyages  or   kept  for  future  use.     Salted 
meat  is  not  as  nutritious  as  fresh,  since  the  brine  absorbs 
its  rich  juices  and  hardens  its  fibres.     Long  continued  use 
of  salt  meats,  without  fresh  vegetables,  gives  rise  to  the 
disease   called   scurvy,   formerly   very  prevalent   on  ship- 
board and  in  prisons ;  but  now  scarcely  known. 

18.  Cooking. — The  preparation  of  food  by  the  agency 


16.  Preference  of  persons?     Venison  ?    Mutton  ?    Cheese  ?    Uncooked  flesh 

17.  Cold  as  a  preserver  ?    Meat  in  Russia?     Beef  and  pork,  how  preserved 
Salted  meat  as  food  ?    Scurvy  * 

18.  The  antiquity  of  the  custom  of  cooking  food?     Object  of  cooking?     Th 
oyster  ?     Raw  meat  as  an  occasional  food  ? 


70  FOOD   AND    DRINK. 


of  fire  is  of  almost  universal  practice,  even  among  the 
rudest,  'nations...  --.The-  object  of  cooking  is  to  render  food 
more  easy —o^ Digestion  by  softening  it,  to  develop  its 
flavor,  aiid  io^faise  its  temperature  more  nearly  to  that  of 
the  body.  A  few  articles  of  flesh-food  are  eaten  un- 
cooked in  civilized  lands,  the  oyster  being  an  instance. 
Raw  meat  is  occasionally  eaten  by  invalids  with  weak 
digestive  powers,  and  by  men  training  for  athletic  con- 
tests. 

19.  In    boiling   meat,  the  water  in  which  it  is  placed 
tends  to  dissolve  its  nutrient  juices.     In  fact,  the  cooking 
may  be  so  conducted  as  to  rob  the  meat  of  its  nourish- 
ment, its  tenderness,  and  even  of  its  flavor.     The  proper 
method,  in  order  to  preserve  or  promote  these  qualities,  is 
to  place  the   meat  in  boiling  water,  which,  after  a  few 
minutes,  should  be  reduced  in  temperature.     In  this  way 
the  intense  heat,  at  first,  coagulates  the  exterior  layers  of 
albumen,  and  imprisons   the   delicate  juices ;  after   that, 
moderate  heat  best  softens  it  throughout.     When  soup  is 
to  be  made,  an   opposite  course  should  be  pursued ;  for 
then  the  object  is  to  extract  the  juices  and  reject  the  fibre. 
Meat,  for  such  purpose,  should  be  cut  in  small  pieces  and 
put  into  cold  water,  which  should  then  be  gradually  raised 
to  boiling  heat. 

20.  Roasting  is  probably  the  best  method  of  cooking 
meat,  especially  "joints"  or  large  pieces,  as  by  this  process 
the  meat  is  cooked  in  its  ow/i  juices.     Roasting  should 
begin  with  intense  heat,  and  be  continued  at  a  moderate 
temperature,  in  order  to  prevent   the   drying  out  of  the 
nutritious  juices,  as  by  this  process  an  outer  coating  or 
crust  of  coagulated  albumen  is  formed.     During  this  pro- 
cess the  meat  loses  one-fourth  of  its  weight,  but  the  loss 
is   almost   wholly   water,   evaporated  by   the   heat.      Too 

19.  Effect  of  boiling  meat?    How  may  the  cooking  be  done?    The  proper 
method  ?    Effect  ?    Making  of  soup  ? 

20.  Roasting?    How  should  it  be  done?    Give  th.5  philo^phy  of  the  proce>s. 
Frying  ? 


FOOD   AND 


intense  or  prolonged  heat  will 
Frying  is  the  worst  possible  meth< 
penetrating  the  meat,  or  other  articli? 
and  hardens  it,  and  thus  renders  it  indigt 

21.  Trichina. — It  should   be   remembered   that   ham, 
sausages,  and  other  forms  of  pork,  should  never  be  eaten 
in  a  raw  or  imperfectly  cooked  condition.     The  muscle  of 
the  pig  is  often  infested  by  a  minute  animal  parasite,  or 
worm,  called  trichina  spiralis.     This  worm  may  be  intro- 
duced alive  into  the  human  body  in  pork  food,  where  it 
multiplies  with  great  rapidity,  and  gives  rise  to  a  painful 
and  serious  disease.      This  disease  has  been  prevalent  in 
Germany,  and  cases  of  it  occur  from  time  to  time  in  this 
country. 

22.  Fish. — The  part  of  fish  that  is  eaten  is  the  muscle, 
just  as  in  the  case  of  the  meats  and  poultry.     It  closely 
resembles  flesh  in   its   composition,  but   is  more  watery. 
Some  varieties  are  very  easy  of  digestion,  such  as  salmon, 
trout,   and  cod:   others  are  quite   indigestible,  especially 
lobsters,  clams,  and  shell-fish  generally.     A  diet  in  which 
fish  enters  as  the  chief  article,  is  ill  adapted  to  strengthen 
mind  or  body,  while  its  continued  use  is  said  to  be  the 
fertile  source  of  nearly  every  form  of  disease  of  the  skin. 
Some  persons  are  so  constituted  that  they  can  eat  no  kind 
of  fish  without  experiencing  unpleasant  results. 

23.  Vegetable  Food. — The  list  of  vegetable  articles 
of  diet  is  a  very  long  one,  including  the  grains  from  which 
our  bread-stuffs  are  made,  the  vegetables  from  the  garden, 
and  the  fruits.     All  the  products  of  the  vegetable  king- 
dom are  not  alike  useful.     Some  are  positively  hurtful; 
indeed,  the  most  virulent  poisons,  as  strychnia  and  prussic 
acid,  are  obtained  from  certain  vegetables.     Again,  of  such 

21 .  What  is  "  Trichina  ?"     How  guarded  against  ? 

22.  What  part  of  fish  is  eaten?    What  does  it  resemble?    Fish  as  food  for 
digestion  ?    Fish  as  a  diet  ? 

23.  List    of   vegetable    articles?    Usefulness   of  the    different   vegetables? 
Strychnia  ?    What  further  is  said  in  relation  to  the  nourishing  and  other  qualities 
of  vegetables  ? 


72  FOOD   AND   DRINK. 

articles  as  have  been  found  good  for  food,  some  are  more 
nourishing  than  others:  some  require  very  little  prepara- 
tion for  use,  while  others  are  hard  and  indigestible,  and 
can  only  be  used  after  undergoing  many  preparatory  pro- 
cesses. Great  care  must  therefore  be  exercised,  and  many 
experiments  made,  before  we  can  arrive  at  a  complete 
knowledge  in  reference  to  these  articles  of  diet.  Tea, 
coffee,  and  other  substances  from  which  drinks  are  made, 
ire  of  vegetable  origin. 

24.  Bread. — Wheat  is  the  principal  and  most  valuable 
kind  of  grain  for  the  service  of  man.     Bread  made  from 
wheat-flour  has  been  in  use  for  many  hundreds  of  years, 
and   on   this  account,  as  well  as   because   of  its   highly 
nourishing  properties,  has  been  aptly  called  "  the  staff  of 
life."     We  never  become  tired  of  good  bread  as  an  article 
of  daily  food. 

The  white  kinds  of  flour  contain  more  starch  and  less 
gluten  than  the  darker,  and  are  therefore  less  nutritious. 
The  hard-grain  wheat  yields  the  best  flour.  In  grinding 
wheat,  the  chaff  or  bran  is  separated  by  a  process  called 
"bolting."  Unbolted  flour  is  used  for  making  brown  or 
Graham  bread. 

25.  The  form  of  bread  most  easily  digested  is  that  which 
has  been  "  leavened,"  or  rendered  porous  by  the  use  of 
yeast,   or  by   some   similar  method.     Unleavened  bread 
requires  much  more  mastication.    Hot  bread  is  unwhole- 
some, because  it  is  not  firm  enough  to  be  thoroughly  mas- 
ticated, but  is  converted  into  a  pasty,  heavy  mass  that  is 
not  easily  digested. 

26.  Wheaten  bread  contains  nearly  every  principle  requi- 
site for  sustaining  life,  except  fat.   This  is  commonly  added 
in  other  articles  of  diet,  especially  in  butter, — "  bread  and 
butter,"  consequently,  forming  an  almost  perfect  article  of 

24.  Wheat?    " Staff  of  life ?"    White  flour?    Hard-grain  wheats  ?    Bolting? 
Graham  bread  ? 

25.  Leavened  bread?    Unleavened?    Hot  bread  ? 

26.  Wheaten  bread  ?    Bread  and  butter  ?    Experiment  on  the  dog  ? 


FOOD   AND    DRINK.  73 


food.  The  following  experiment  is  recorded :  "  A  dog 
eating  ad  libitum  of  white  bread,  made  of  pure  wheat,  and 
freely  supplied  with  water,  did  not  live  beyond  fifty  days. 
He  died  at  the  end  of  that  time  with  all  the  signs  of 
gradual  exhaustion."  Death  took  place,  not  because  there 
was  anything  hurtful  in  the  bread,  but  because  of  the 
absence  of  one  or  more  of  the  food-principles. 

27.  The  Potato. — The  common  or  Irish  potato  is  the 
vegetable  most  extensively  used  in  this  country  and  Great 
Britain.     Among  the  poorer  classes  in   Ireland  it  is  the 
main  article  of  food.     While  it  is  not  so  rich  in  nutritious 
substances  as  many  others,  it  has  some  very  useful  qualities. 
It  keeps  well  from  season  to  season,  and  men  do  not  weary 
of  its  continuous  use.     It  is  more  than  two-thirds  water, 
the  balance  being  chiefly  starch,  with  a  little  albumen. 

28.  The  sweet  potato  differs  from  the  white  or  common, 
in  containing  more  water  and  a  small  proportion  of  sugar. 
The  common  potato  and  the  tomato  belong  to  the  same 
botanical  order  as  the  "nightshades,"  but  do  not  possess 
their  poisonous  qualities,  unless  we  except  potatoes  that 
are  in  the  process  of  germination  or  sprouting,  when  they 
are  found  injurious  as  food. 

29.  Fruits. — These  are  produced,  in   this   country,  in 
great  abundance,  and  are  remarkable  alike  for  their  variety 
and  delicious  flavor ;     consequently  they  are  consumed  in 
large   quantities,   especially   during  the  warmer  months. 
The    moderate   use    of    ripe    fruits,    in    their   season,    is 
beneficial,  because  they  offer  a  pleasant  substitute  for  the 
more  concentrated  diet  that  is  used  in  cold  weather.     The 
amount    of    solid    nutriment    they   contain    is,   however, 
small.     The  percentage  of  water  in  cherries  is  seventy- 
five,  in  grapes  eighty-one,   in  apples  eighty  two.     Unripe 
fruits  contain  starch,  which,  during  the  process  of  ripening, 

27.  State  what  is  said  of  the  Irish  potato  ? 

28.  Sweet  potato  ?    Nightshades  ?    Potatoes  when  germinating? 

29.  Fruits?    Use  of  ripe  fruit?    Nutriment  they  contain?    Starch  in  unripe 
fruits  ?     Cooking  of  unripe  fruits  ? 

4 


74  FOOD   AND    DRINK. 


is  converted  into  sugar.  Such  fruits  are  indigestible  and 
should  be  avoided :  cooking,  however,  in  part  removes  the 
objections  to  them. 

30.  Pure  Water. — It  is  important  that  the  water  we 
drink  and  use  in  the  preparation  of  food  should  be  pure. 
It  should  be  clear  and  colorless,  with  little  or  no  taste  or 
smell,  and  free  from  any  great  amount  of  foreign  ingre- 
dients.    Chemically  pure  water  does  not  occur  in  nature  : 
it  is  only  obtained  by  the  condensation  of  steam,  carefully 
conducted,  and  is  not  as  agreeable  for  drinking  purposes 
as  the  water  furnished  by  springs  and  streams.     Rain-water 
is  the  purest  occurring  in  nature ;  but  even  this  contains 
certain  impurities,  especially  the  portion  which  falls  in  the 
early  part  of  a  shower;  for  in  its  descent  from  the  clouds, 
the  particles  floating  in  the  air  are  caught  by  the  falling 
drops. 

31.  Water  from  springs  and  wells  always  contains  more 
or  less  foreign  matter  of  mineral  origin.     This  imparts  to 
the  drink  its  pleasant  taste — the  sparkle,  or  "  life,"  coming 
from  the  gases  absorbed  by  the  water  during  its  passage 
under  ground.     The  ordinary  supply  of  cities  is  from  some 
pure  stream  or  pond  conveyed  from  a  distance  through 
pipes,  the  limpid  fluid  containing  generally  only  a  small 
amount  of  impurity.     Croton  water,  the  supply  of  New 
York  City,  is  very  pure,  and  contains  only  four  and  a  half 
grains  to  a  gallon :  the  Ridgewood  water  of  Brooklyn  holds 
even  less  foreign  matter. 

32.  Drinking- water  may  contain  as  large  a  proportion  as 
sixty  to  seventy  grains  per  gallon  of  impurity,  but  a  much 
larger    quantity  renders  it   unwholesome.     The    mineral 
spring  waters,  used  popularly   as   medicines,  are   highly 
charged  with  mineral  substances.     Some  of  them,  such  as 

30.  How  should  drinking-water  be  as  regard?  color  and  smell?     Chemically 
pure  water  ?     How  obtained  ?    Agreeablenes-s  of  perfectly  pure  water  ? 

31.  Spring  and  well  water?     Whence  the  sparkle,  or  life?    The  water  supply 
of  cities  ?    Croton  wate  ?    Ridgewood  ? 

32.  Impurities  in  drinking-water?    Mineral  springs  ? 


FOOD   AND   DRINK.  75 


the  waters  at  Saratoga,  contain  three  hundred  grains  and 
more  to  the  gallon. 

33.  Action  of  Water  upon  Lead. — The  danger  of 
using  water  that  has  been  in  contact  with  certain  metals  is 
well  known.     Lead  is  one  of  the  most  readily  soluble,  and 
probably  the  most  poisonous  of  these  substances  in  common 
use.     When  pure  water  and  an  untarnished  surface  of  lead 
come  in  contact,  the  water  gradually  corrodes  the  metal, 
and  soon  holds  an  appreciable  quantity  of  it  in  solution. 
When  this  takes  place  the  water  becomes  highly  injurious: 
the  purer  the  water,  and  the  more  recent  the  use  of  the 
metal,  the  greater  will  be  the  danger. 

34.  In  cities,  lead  pipes  are  commonly  used  to  convey 
water  through  the  houses ;  lead  being  also  used  in  the  con- 
struction of  roofs,  cisterns,  and  vessels  for  keeping  water 
and  other  liquids.     After  the  articles  of  lead  have  been  in 
use  several  months,  the  danger  of  lead-poisoning  dimin- 
ishes.    An  insoluble  coating  of  the  sulphate  of  lead  forms 
upon  the  exposed  surface,  thus  protecting  it  from  further 
corrosion.    It  is,  however,  a  wise  precaution,  at  all  times  to 
reject  the  water  or  other  fluid  that  has  been  in  contact 
with  leaden  vessels  over  night,  or  for  a  number  of  hours. 
Allow  the  water  in  pipes  to  run  freely  before  using. 

35.  Coffee. — This  is  an  important  addition  to  diet,  and 
if  moderately  used  is  beneficial  to  persons  of  adult  age. 
As  commonly  employed,  it  consists  of  an  infusion  in  boil- 
ing water  of  the  roasted  and  ground  berry.     The  water 
extracts  certain  flavoring  and  coloring  matters,  but  that 
which  gives  it  its  peculiar  stimulant  qualities  is  the  alka- 
loid caffein.     With  most  persons  its  action  is  that  of  a 
gentle  stimulant,  without  any  injurious  reaction.     It  pro- 
duces a  restful  feeling  after  exhausting  efforts  of  mind  or 


33.  What  is  stated  of  the  action  of  water  upon  lead  ? 

34.  Lead  in  pipes  and  other  things  ?     Advice  ?    What  takes  place  after  the  arti, 
cles  of  lead  have  been  used  much  ?    What  is  wise  ? 

35.  Coffee  as  an  article  of  diet?    Of  what  does  it  consist?    How  does  the 
water  affect  the  coffee?    The  peculiar  stimulant  ?    How  does  it  affect  most  per 


7(?  FOOD    AND    DRINK. 


body;  it  tranquilizes,  but  does  not  disqualify  for  labor; 
and  hence  it  is  highly  esteemed  by  persons  of  literary  pur- 
suits. 

36.  Another  property  of  coffee  is,  that  it  diminishes  the 
waste  of  the  tissues,  and  consequently  permits   the  per- 
formance of  excessive  labor  upon  an  economical  and  in- 
adequate diet.     This  has  been  tested  among  the  miners  of 
Belgium.     Their  allowance  of  solid  food  was  below  that 
found  necessary  in  prisons  and  elsewhere;  but,  with  the 
addition  of  about  four  pints  of  coffee  daily,  they  were  en- 
abled to  undergo  severe  labor  without  reducing  their  mus- 
cular strength.     The  caravans  which  traverse  the  deserts 
are  supported  by  coffee  during  long  journeys  and  length- 
ened privation  of  food.     Among  armies  it  is  indispensable 
in  supplementing  their  imperfect  rations,  and  in  relieving 
the  sense  of  fatigue  after  great  exposure  and  long  marches. 
When  taken  with  meals,  coffee  is  also  thought  to  promote 
digestion. 

37.  Tea. — The  effects  of  tea-drinking  are  very  similar 
to  those  of  coffee,  and  are  due  to  a  peculiar  principle  called 
thein.     This  principle  is  probably  the  same  as  that  found 
in  coffee,  caffein,  since  the  chemical  composition  of  both 
is  precisely  alike.     Tea,  as  a  beverage,  is  made  from  the 
dried  leaves  of  the  plant  by  the  addition  of  hot  water;  if 
the  tea  is  boiled,  the  oil  which  gives  it  its  agreeable  flavor 
is  driven  off  with  the  steam.      There  are  two  kinds  of 
tea — the  black  and  the  green :  the  latter  is  sometimes  in- 
jurious, producing  wakefulness  and  other  nervous  symp- 
toms.    The  excessive  use  of  either  coffee  or  tea  will  cause 
wakefulness. 

38.  During  Dr.  Kane's  expedition  in  the  Arctic  regions, 
the  effects  of  these  articles  were   compared.     "After  re- 


36.  Another    property   of    coffee?     Miners  of    Belgium?     The    Caravans? 
A  MI  ong  armies?    Taken  with  meals? 

37.  Effects   of  tea-drinking?     Peculiar  principle?     The  tea  beverage,  how 
made  ?     Black  and  green  tea  ?    Excessive  use  of  tea  or  coffee  ? 

38.  Experiments  made  during  Kane's  expedition  ? 


FOOD    AtfB    DRINK.     '  77 


peated  trials,  the  men  took  most  kindly  to  coffee  in  the 
morning  and  tea  in  the  evening.  The  coffee  seemed  to 
continue  its  influence  throughout  the  day,  and  they  seemed 
to  grow  hungry  less  rapidly  than  after  drinking  tea,  while 
tea  soothed  them  after  a  day's  hard  labor,  and  the  better 
enabled  them  to  sleep.  They  both  operated  upon  fatigued 
men  like  a  charm,  and  their  superiority  over  alcoholic 
stimulants  was  very  decided." 

39.  Chocolate  is  made  from  the  seeds  of  the  cocoa-tree, 
a  native  of  tropical  America.     Its  effects  resemble  some- 
what those  of  tea  and  coffee,  but  it  is  very  rich  in  nutri- 
ment.   Linnaeus,  the  botanist,  was  so  fond  of  this  beverage, 
that  he  gave  to  the  cocoa-tree  the  name,  Theobrovia — "  the 
Food  of  the  Gods."     Its  active  principle  is  theobromin. 

40.  Alcohol. — The  list  of  beverages  that  are  consumed 
for  the  sake  of  the  alcohol  they  contain  is  a  very  long  one. 
Their  use  is  almost  universally  prevalent,  every  civilized 
nation,  and  nearly  every  barbarous  one,  having  its  favorite 
alcoholic  drink ;  and,  as  a  general  rule,  the  nations  which 
stand  the  highest  in  civilization  have  the  greatest  varieties 
of  these  beverages, — at  the  same  time  using  them  the  most 
intelligently  and  wisely. 

41.  The  wines  and  malt  liquors  that  contain  a  small 
amount  of  alcohol  are  produced  by  fermentation.      The 
beverages  that  hold   a  large   proportion  of  alcohol,   the 
"  ardent  spirits,"   are   made    by   distillation.      Enormous 
quantities  of  grains   and  fruits   are  thus  yearly  diverted 
from  their  proper  uses  as  food ;  some  of  these  being  corn, 
wheat,  rye,  barley,  potatoes,  and  rice ;  also  the  grape,  apple, 
pear,  peach,  sugar-cane,  cherry,  fig,  and  orange.    Wine,  the 
fermented  juice  of  the  grape,  has  been  in  use  from  time 
immemorial,  while   the   introduction  of  distilled   liquors 
dates  from  a  comparatively  recent  period. 

39.  State  what  is  said  of  chocolate. 

40.  Use  of  alcoholic  drink:?,  how  general  ">    The  rule  given  1 

41 .  The  beverages  produced  by  fermentation  ?   The  ardent  spirits  '!   Grains  and 
fruits  employed  ?     Long  use  of  wine  ?     Of  distilled  liquors  ? 


78  FOOD    ANJ)    JJULNK. 


42.  What  is  the  physiological  action  of  alcohol  ?   Its  first 
and  most  evident  action  is  stimulation  :  this  effect  is  tran- 
sient, and  is  followed  by  a  variable  degree  of  depression. 
At  first  it  sharpens  the  appetite  and  quickens  digestion, 
but  its  habitual  use  impairs  both.     This  stimulation  is 
efficient  in  giving  the  system  an  artificial  strength  during 
some  temporary  derangement,  and  in  enabling  the  endur- 
ance of  unusual  fatigue  or  exposure.     The  experience  of 
Dr.  Hayes,  and  other  explorers  of  the  polar  regions,  is  that 
alcohol  does  not  enable  the  body  to  resist  the  influence  of 
cold,  but,  on  the  contrary,  is  always  injurious. 

43.  Another  property  it  has  in  common  with  tea  and 
coffee.    It  supports  the  powers  of  life,  economizes  food,  and 
retards  the  waste  of  tissues ;  in  other  words,  it  "  banks  the 
fires,"  and  prevents   their  burning  wastefully.      On  this 
principle  we  explain  the  restorative  influence  of  wines  or 
liquors  during  exhausting  diseases,  in  convalescence,  and 
after  excessive  labors  of  mind  or  body. 

44.  Pure   alcohol,   or  an  excessive   quantity   of   ardent 
spirits,  is  an  undoubted   poison,  and   has   been   frequently 
known  to  produce  fatal  results.     Stimulants  in  moderate 
quantities  have  been  thought  to  increase  strength,  and  in 
this  view  they  have  been  called  "alcoholic  foods."     This  is 
not  now  conceded  by  scientific  men.     The  prevailing  opin- 
ion is,  that  they  serve  no  useful  purpose  as  an  article  of 
diet,  and  that  their  beneficial  influence  is  limited  to  cases 
where  the  system  is  enfeebled,  where  some  unnatural  de- 
mand is  made  upon  the  vital  powers,  or  where  the  supply 
of  food  is  insufficient.     Hence,  while  alcohol  has  not  the 
power  to  build  up,  it  may  obstruct  the  process  of  pulling 
down. 


42.  Describe  the  aciton  of  alcohol  upon  the  human  system?    Experience  of 
Dr.  Hayes  and  others  ? 

43.  Another  property  of  alcohol  ?    How  do  we  explain  the  restorative  influence 
of  wines  and  liquors  ? 

44.  Alcohol,  a  poison?    Moderate  stimulants ?    Prevailing  opinion  ?    Hence? 


REVIEW   QUESTIONS.  79 


QUESTIONS  FOE  TOPICAL  KEVIEW. 

PAGE 

1.  How  is  the  necessity  for  food  shown  ? ^4 

2.  To  what  process  of  waste  and  repair  is  the  body  constantly  subjected  ? 64 

3.  How  do  you  account  for  the  sensations  of  hunger  and  thirst  ?  05 

4.  What  further  can  you  state  having  relation  to  the  subject  ? .65 

5.  What  can  you  state  in  regard  to  the  quantity  of  food  required  for  the 

support  of  life  ? ^  66 

6.  What  circumstances  change  the  needs  of  persons,  old  and  yonng,  as  re- 

gards food  and  drink? "'  65  67 

7.  What  becomes  of  all  the  food  and  drink  we  consume  ? '  gg 

8.  What  further  can  you  state  in  relation  to  the  process  of  renovation  through 

.  which  the  body  passes  ? gg 

9.  What  can  you  state  of  the  habits  of  nations  in  respect  to  diet  ? 66,  67,  69 

10.  What  in  relation  to  the  selection  of  articles  for  food  ? 67 

11.  What  as  respects  the  necessity  for  changing  or  varying  the  diet  ? 67 

12.  What  has  been  proved  as  regards  animal  food  ? 67 

13.  Of  what  importance  is  milk  as  an  article  of  food  ? 67,  68 

14.  What  are  the  constituents  of  milk  ? 68 

15.  What  can  you  state  of  eggs  as  an  article  of  food  ? 68 

16.  Of  the  meats,  so  called,  as  an  article  of  food  ? 68,  6!) 

17.  What  effect  does  cold  have  upon  meats  ? 69 

18.  In  what  other  way  may  beef  and  pork  be  preserved  ? <j9 

19.  What  can  you  state  of  salted  meat  as  food,  and  of  its  continued  use  ? 59 

20.  What  change  does  meat  undergo  in  the  cooking  ? 70,  71 

21.  What  directions  are  given  for  boiling  meat  ?  70 

22.  What  for  roasting,  and  with  what  results  ? 70,  71 

23.  What  is  said  about  the  frying  of  meats  ? 71 

24.  Give  the  statement  in  relation  to  trichina 71 

25.  State  what  is  said  in  relation  to  fish 71 

26.  What  is  stated  of  the  usefulness  and  other  properties  of  the  products  of 

the  vegetable  kingdom  ? 71,  72 

27.  What  further  is  said  of  vegetable  food  ? 71,  72 

28.  Why  is  bread  made  of  wheat  flour  so  important  as  an  article  of  food  ? 72 

29.  State  whatever  else  you  can  in  relation  to  bread 72,  73 

30.  Give  the  statement  respecting  the  potato 73 

31.  What  is  stated  of  fruits,  the  use  of  them,  their  nutritious  qualities,  etc.?  73,  74 

32.  How  general  is  the  existence  of  perfectly  pure  water  ? 74 

33.  What  is  stated  in  relation  to  drinking  water  ? 74,  75 

34.  How  does  the  action  of  water  upon  lead  affect  lead  ? 75 

35.  What  further  can  you  state  on  the  subject  ? 75 

36.  What  properties  has  coffee  as  an  article  of  diet  ? 75.  76 

37.  In  what  circumstances  has  coffee  been  found  peculiarly  beneficial  ? 76 

38.  What  comparison  is  made  between  coffee,  tea,  and  chocolate  ? 76 

39.  How  are  the  wines,  and  malt  and  other  alcoholic  beverages  produced  ? 77 

40.  What  articles  are  employed  in  their  production  ? 77 

41.  Describe  the  physiological  action  of  alcohol 78 

42.  What  comparison  is  made  between  tea,  coffee,  and  alcohol  ? 78 

43.  What  can  you  state  of  alcohol,  as  a  poison,  a  stimulant,  and  article  of  diet  ?  78 

44.  What,  then,  can  be  said  of  alcohol  as  a  recommendation  ? 73 


80  DIGESTION. 


CHAPTER  VI. 
DIGESTION. 

TJw  Principal  Processes  of  Nutrition — The  General  Plan  of  Digestion 
—Mastication — Tlie  Teeth — Preservation  of  the  Teeth — Insalivation 
— The  Stomach  and  tlte  Gastric  Juice — The  Movements  of  tlie 
Stomach — Gastric  Digestion — The  Intestines — TJie  Bile  and  Pan- 
creatic Juice — Intestinal  Digestion — Absorption  by  means  of  Blood- 
vessels and  Lacteals — Tlie  Lymphatic  or  Absorbent  System — The 
Lymph — Conditions  which  affect  Digestion — The  Quality,  Quan- 
tity, and  Temperature  of  Hie  Food — The  Influence  of  Exercise  and 
Sleep. 

1.  Nutrition. — The  great   design   of  food  is   to  give 
nutriments  nourishment  to   the  body.     But  this  is  not 
accomplished  directly,  as  the  food  must  first  pass  through 
certain  preparatory  changes,  as  follows :    (1),  Digestion,  by 
which  the  food  is  reduced  to  a  soluble  condition;  (2),  Ab- 
sorption, by  which,  when  digested,  it  is  imbibed  into  the 
blood;  (3),  Circulation,  which  carries  the  enriched  blood 
to  the  various  parts  of  the  system;  and  (4),  Assimilation. 
by  which  each  tissue  derives  from  the  blood  the  materials 
necessary  for  its  support. 

2.  By  these  means  the  sustaining  power  of  food  is  grad- 
ually  developed   and  employed,  and  the  vital  machinery 
kept  in  working  order,  somewhat  after  the  manner  of  the 
steam-engine.     To  operate  the  latter,  the  force  imprisoned 
within  the  coal  and  water  is  set  free  and  converted  into 
motion  by  the  combustion  of  the  fuel  and  the  vaporization 
of  the  water.     It  will  be  seen,  however,  when  we  come  to 
study  these  operations  in  the  human  body,  that  they  are 
conducted  silently  and  harmoniously,  with  marvellous  deli- 
cacy and  completeness,  and  without  that  friction,  and  con- 


1 .  Design  of  food  ?    How  accomplished  ? 

2.  Sustaining  power  of  food  ?    Simile  of  the  engine  ?     Operation  in  the  human 
body  ? 


DIGESTION. 


81 


sequent  loss  of  power,  which  attend  the   working  of  the 
most  perfect  machinery  of  man's  invention. 

3.  General  Plan  of  Digestion. — The  great  change 
which  food  undergoes  in  digestion  is  essentially  a  reform- 
ing process,  reducing  articles  of 

diet,  which  are  at  first  more  or 
less  solid,  crude,  and  coarse,  to 
a  liquid  and  finely  comminuted 
condition,  suitable  for  absorption 
into  the  blood.  The  entire  pro- 
cess of  digestion  takes  place  in 
what  is  called  the  alimentary 
canal,  a  narrow,  tortuous  tube, 
about  thirty  feet  in  its  entire 
length.  This  canal  begins  in 
the  mouth,  extends  thence  down- 
ward through  the  gullet  to  the 
stomach  (a  receptacle  in  which 
the  principal  work  of  digestion 
is  performed),  and  thence  onward 
through  the  small  and  large  in- 
testines'. 

4.  The  stomach  and  intestines 
are  situated  in  the  cavity  of  the 

attfomen  (Fig.  16,  C,  and  Fig.  22),  FlG  16._SECTION  op  THE  TRUNK 

and   OCCUpy   about  two-thirds    of      SHOWING  THE  CAVITIES  OP  THE 
. ,  rf.,  , .  .  .   ,    .,          CHEST  AND  ABDOMEN. 

its  space.  The  action  to  which  the         A<  CaVit,y  of  chest ; 
food  is  subjected  in  these  organs         c' Abffi5?; 
is  of  two  kinds— mechanical  and         D* E' Spinal  bolumn- 
chemical.     By  the  former  it  is  crushed,  agitated,  and  car- 
ried onward  from  one  point  to  another;  by  the  latter  it  is 
changed  in  form  through  the  solvent  power  of  the  various 
digestive  juices. 


3.  Change  of  food  in  digestion?    Process  of  digestion?    Describe  the  alimen- 
tary canal. 

4.  Situation  of  the  stomach  and  intestines  ?     Action  of  the  food  ?     Mechanical 
action  ?    Chemical  ? 

4* 


DIGESTIOX. 


5.  Mastication. — As  soon  as  solid  food  is  taken  into 
the  mouth,  it  undergoes  mastication,  or  chewing.  It  is 
caught  between  the  opposite  surfaces  of  the  teeth,  and  by 
them  is  cut  and  crushed  into  very  small  fragments.  In 

the  movements  of  chewing, 
the  lower  jaw  plays  the  chief 
part;  the  upper  jaw,  having 
almost  no  motion,  acts  sim- 
ply as  a  point  of  resistance, 
to  meet  the  action  of  the 
former.  These  movements 
of  the  lower  jaw  are  of  three 
sorts:  a  vertical  or  cutting, 
a  lateral  or  grinding,  and  a 
to-and-fro  or  gnawing  mo- 
tion. 

6.  The  teeth  are  composed 
of  a  bone-like  material,  and 
are  held  in  place  by  roots 
running  deeply  into  the  jaw. 
exposed  portion,  or 
is  protected  by  a 
thin  layer  of  enamel  (Fig. 
17,  «),  the  hardest  substance 
in  the  body,  and,  like  flint,  is  capable  of  striking  fire  with 
steel.  In  the  interior  of  each  tooth  is  a  cavity,  containing 
blood-vessels  and  a  nerve,  which  enter  it  through  a  minute 
opening  at  the  point  of  the  root  (Fig.  19). 

7.  There  are  two  sets  of  teeth ;  first,  those  belonging  to 
the  earlier  years  of  childhood,  called  the  milk  teeth,  which 
are  twenty  in  number  and  small.  At  six  or  eight  years  of 
age,  when  the  jaw  expands,  and  when  the  growing  body 
requires  a  more  powerful  and  numerous  set,  the  roots  of 


PIG.  17.— SECTION  OF  A  TOOTH. 

a,  Enamel;    b.  Cavity-    cc,  Roots: 

d,  Body  of  the  Tooth. 


The 


"  crown," 


5.  Describe  the  process  of  mastication  ?    How  many  and  what  movements  ? 

6.  Composition  of  the  teeth  ?    Enamel  of  the  teeth  ?    Interior  of  teeth  * 

7.  The  milk  teeth  ?    The  permanent  teeth  ? 


DIGESTION. 


83 


the  milk  teeth  are  absorbed,  and  the  latter  are  "shed."  or 
fall  out,  one  after  another  (Fig.  18),  to  make  room  for  the 
permanent  set. 


PIG.  18.— SECTION  OF  THE  JAWS. 
1'  2'  3'  4   5'.  The  Milk  Teeth ;  1"  to  8",  The  Germs  of  the  Permanent  Set. 

8.  There  are  thirty-two  teeth  in  the  permanent  set,  as 
many  being  in  one  jaw  as  the  other.  Each  half-jaw  has 
eight  teeth,  similarly  shaped  and  arranged  in  the  same 
order :  thus,  two  incisors,  one  canine,  two  bicuspids,  and 
three  molars.  The  front  teeth  are  small,  sharp,  and  chisel- 
edged,  and  are  well  adapted  for  cutting  purposes;  hence 
their  name  incisors.  The  canines  stand  next,  one  on  each 
side  of  the  jaw;  these  receive  their  name  from  their  resem- 
blance to  the  long,  pointed  tusks  of  the  dog  (Fig.  19). 


8,9.  Number  of  teeth  ?    How  distributed  ? 


84 


DIGESTION. 


9.  The  bicuspids,  next  in  order,  are  larger  and  have  a 
broader  crown  than  the  former;  while  behind  them  are 
the  molars,  the  largest  and  most  powerful  of  the  entire  set. 
These  large  back  teeth,  or  "  grinders,"  present  a  broad, 
rough  surface,  suitable  for  holding  and  crushing  the  food. 


FIG.  19.— SECTION  op  THE  JAWS— RIGHT  SIDE. 

V,  A,  N.  Veins.  Arteries,  and  Nerves  of  the  Teeth.  The  root  of  one  tooth  in  each 
jaw  is  cut  vertically  to  show  the  cavity  and  the  blood-vessels,  etc.,  \\ithm  H. 
1  to  8,  Permanent  Teeth. 

The  third  molar,  or  "  wisdom  tooth,"  is  the  last  to  be  cut, 
and   does   not   appear   until   about  the  twenty-first  year. 


DIGESTION.  85 


The  order  of  arrangement  of  the  teeth  is  indicated  by  the 
following  dental  formula: — 

M-     "s~~     -M 
B'''          ~XB 

c/4\c 
I 

10.  It  is  interesting,  at  this  point,  to  notice  the  different 
forms  of  teeth  in  different  animals,  and  observe  how  ad- 
mirably their  teeth  are  suited  to  the  respective  kinds  of 
food  upon  which  they  subsist.     In  the  carnivora,  or  flesh- 
feeders,  the  teeth  are  sharp  and  pointed,  enabling  them 
both  to  seize  their  prey,  and  tear  it  in  pieces ;  while  the 
herbivora,  or  vegetable- feeders,  have  broad,  blunt   teeth, 
with  rough  crowns,  suitable  for  grinding  the  tough  grasses 
and  grains  upon  which  they  feed.     Human  teeth  partake 
of  both  forms ;  some  of  them  are  sharp,  and  others  are 
blunt ;  they  are  therefore  well  adapted  for  the  mastication 
of   both    flesh    and   vegetables.      Hence   we   argue   that, 
although  man  may  live  exclusively  upon  either  vegetable 
or  animal  food,  he  should,  when  possible,  choose  a  diet 
made  up  of  both  varieties. 

11.  Preservation  of  the  Teeth. — In  order  that  the 
teeth  shall  remain  in  a  sound  and  serviceable  condition, 
some  care  is  of  course  requisite.     In  the  first  place,  they 
require  frequent  cleansing ;  for  every  time  we  take  food, 
some  particles  of  it  remain  in  the  mouth ;  and  these,  on 
account  of  the  heat  and  moisture  present,  soon  begin  to 
putrefy.     This  not  only  renders  the  breath  very  offensive, 
but  promotes  decay  of  the  teeth. 

10.  Different  forms  of  teeth  ?    Human  teeth  ?    The  inference  ? 

1 1 .  Cleaning  of  teeth  ?    Effects  of  not  cleaning  ? 


SG  DIGESTION. 


12.  The  saliva,  or  moisture  of  the  mouth,  undergoes  a 
putrefactive  change,  and  becomes  the  fertile  soil  in  which 
a  certain  minute  fungus  has  its  growth.     This  fluid,  too,  if 
allowed  to  dry  in  the  mouth,  collects  upon  the  teeth  in  the 
form   of  an   unsightly,   yellow   concretion,   called   tartar. 
To  prevent  this  formation,  and  to  remove  other  offensive 
substances,  the  teeth   should  be  frequently  cleaned  with 
water,  applied  by  means  of  a  soft  tooth-brush.     The  de- 
struction of  the  tartar  fungus  is  best  effected  by  the  use 
of  a  weak  solution  of  carbolic  acid. 

13.  Again,  it  should  be  borne  in  mind  that  the  enamel, 
Nature's  protection  for  the  teeth,  when  once  destroyed,  is 
not  formed  anew ;  and  the  body  of  the  tooth  thus  exposed, 
is  liable  to  rapid  decay.     On  this  account,  certain  articles 
are  to  be  guarded  against ;  such  as  sharply  acid  substances 
that  corrode  the  enamel,  and  hard  substances  that  break 
or  scratch  it — as  gritty  tooth  powders,  metal  tooth  picks, 
and  the  shells  of  hard   nuts.     Sudden  alternations  from 
heat  to  cold,  when  eating  or  drinking,  also  tend  to  crack 
the  enamel. 

14.  Insalivation. — When  the  morsel  of  food  is*  cut  and 
ground  by  the  teeth,  it  is  at  the  same  time  also  intimately 
mixed  with  the  saliva,  or  fluids  of  the  mouth.     This  con- 
stitutes the  second  step  of  digestion,  and  is  called  insaliva- 
tion.     The  saliva,  the  first  of  the  digestive  solvents,  is  a 
colorless,  watery,  and    frothy  fluid.      It  is  secreted  (i.  e. 
separated  from  the   blood)  partly  by  the  mucous  mem- 
brane which  lines  the  mouth ;  but  chiefly  by  the  salivary 
glands,  of  which  there  are  three  pairs  situated  near  the 
mouth. 

15.  These    glands    consist    of   clusters    of   very   small 


12.  Effects  upon  the  saliva?    Formation  of  tartar?    How  prevented?     How 
destroyed  ? 

13.  Destruction  of  the  enamel  *    How  enarded  against? 

1 4.  Mixing  of  food  with  the  saliva  V    What  is  the' saliva  ?    How  secreted  ?    The 
salivary  glands? 

1 5.  The  flow  of  saliva  ?    The  thought  of  food  ?    Anxiety  and  grief?    Animals 
fed  upon  dry  and  coarse  food  ? 


DIGESTION. 


pouches,  around  which  a  delicate  network  of  blood-vessels 
is  arranged:  they  empty  into  the  mouth  by  means  of 
little  tubes,  or 
ducts.  The  flow 
from  these  glands 
is  at  all  times  suf- 
n'cient  to  maintain 
a  soft  and  moist 
condition  of  the 
tongue  and  mouth; 
but  when  they  are 
excited  by  the  pres- 
ence and  taste  of 
food,  they  pour 

forth       the      Saliva          FlG-  20-— STRUCTURE  OP  A  SALIVARY  GLAND. 

more  freely.  Even  the  mere  thought  of  food  will  at 
times  cause  the  saliva  to  flow,  as  when  the  appetite  is 
stimulated  by  the  sight  or  smell  of  some  savory  article ;  so 
that  the  common  expres- 
sion is  correct  that  "  the 
mouth  waters"  for  the  fa- 
vorite articles  of  food. 
Anxiety  and  grief  prevent 
its  flow,  and  cause  "the 
tongue  to  cleave  to  the 
roof  of  the  mouth."  In 
the  horse  and  other  ani- 
mals, that  feed  upon  dry 
and  coarse  fodder,  and  re- 

-i          -t  FIG.  21.— THE  HEAD  OP  A  HORSE,  showing  the 

quire    an    abundant    SUp-       large  salivary  gknd  (a),  its  duct  (6),  the 

ply  of  saliva,  we  find  large 

salivary  glands,  as  well  as  powerful  muscles  of  mastication. 

16.  The  mingling  of  the  saliva  with  the  food  seems  a 

simple  process,  but  it  is  one  that  plays  an  important  part 


1 6.  Importance  of  the  process  ?    The  first  place  ?    The  second  ?    The  third  ? 


88  DIGESTION. 


in  digegtion.  In  the  first  place,  it  facilitates  the  motions 
of  mastication,  by  moistening  the  food  and  lubricating  the 
various  organs  of  the  mouth.  Secondly,  it  prepares  the 
way  for  other  digestive  acts:  by  the  action  of  the  teeth, 
the  saliva  is  forced  into  the  solid  food,  softens  the  harder 
substances,  and  assists  in  converting  the  whole  morsel  into 
a  semi-solid,  pulpy  mass,  that  can  be  easily  swallowed,  and 
readily  permeated  by  other  digestive  fluids.  The  saliva 
also,  by  dissolving  certain  substances,  as  sugar  and  salt, 
develops  the  peculiar  taste  of  each  ;  whereas,  if  the  tongue 
be  dry  and  coated,  they  are  tasteless.  Hence,  if  substances 
are  insoluble,  they  are  devoid  of  taste. 

17.  Finally,  the  saliva  has  the  property  of  acting  chemi- 
cally upon  the  food.    As  we  have  before  stated  (Chap.  IV.), 
starch,  as  starch,  cannot  enter  the  tissues  of  the  body ;  but, 
in  order  to  become  nutriment,  must  first  be  changed  to 
grape  sugar.    This  change  is,  in  part,  effected  by  the  saliva, 
and  takes  place  almost  instantly,  whenever  it  comes  in  con- 
tact with  cooked  starch.     This  important  function  is  due 
to   an   organic   ingredient  of  the   saliva  •  called     ptyalin. 
This   substance  has   been   extracted  from   the   saliva   by 
the   chemist,   and    has    been    found,    by   experiment,   to 
convert  into  sugar  two  thousand  times  its  own  weight  of 
starch. 

18.  Importance  of   Mastication  and    Insaliva- 
tion. — Each   of  these  processes  complements   the   other, 
and  makes  the  entire  work  available;   for,  by  their  joint 
action,  they  prepare  the  food  in  the  best  possible  manner 
for  further  digestive  changes.     The  knowledge  of  these 
preliminary  functions  will   appear   the    more   important, 
when  we  reflect  that  they  are  the  only  ones  which  we  can 
regulate  by  the  will.     For,  as  soon  as  the  act  of  swallowing 
begins,  the  food  not  only  passes  out  of  sight,  but  beyond 


IT.  Its  final  importance ?    Starch ?    How  effected  ?    Ptyalin  ? 
18.  Each  of  the  processes?    Why  is  a  knowledge  of  the  digestive  function 
important  ?    How  shown  ? 


DIGESTION.  89 


control ;  and  the  subsequent  acts  of  digestion  are  conse- 
quently involuntary  and  unconsciously  performed. 

19.  It  is  generally  known  that  rapid  eating  interferes 
with  digestion.     How  does  this  occur  ?    In  the  first  place, 
in  rapid  eating,  the  flow  of   the  saliva  is  insufficient  to 
moisten  the  solid  parts  of  the  food,  so  that  they  remain  too 
hard  and  dry  to  be  easily  swallowed.     This  leads  to  the 
free  and  frequent  use  of  water,  or  some  other  beverage,  at 
meals,  to  "  wash  down"  the  food, — a  most  pernicious  prac- 
tice.    For  these  fluids,  not  only  cannot  take  the  place  of 
the  natural  digestive  juices,  but,  on  the  contrary,  dilute 
and  weaken  them. 

20.  Secondly,  the  saliva  being  largely  the  medium  of  the 
sense  of  taste,  the  natural  flavors  of  the  food  are  not  devel- 
oped, and  consequently  it  appears  comparatively  insipid. 
Hence   the   desire   for  high-seasoned  food,   and  pungent 
sauces,  that   both  deprave  the  taste  and  over  excite  the 
digestive  organs.     Rapid  eating  also  permits  the  entrance 
of  injurious  substances  which  may  escape  detection  by  the 
taste,  and  be  unconsciously  received  into  the  system.     In 
some  instances,  the  most  acrid  and  poisonous  substances 
have  frequently  been  swallowed  "  by  mistake,"  before  the 
sense  of  taste  could  act,  and  demand  their  rejection. 

21.  Thirdly,  the  food,  being  imperfectly  broken  up  by 
the  teeth,  is  hurried  onward  to  the  stomach,  to  be  by  it 
more  thoroughly  divided.    But  the  task  thus  imposed  upon 
the  stomach,  it  is  not  at  all  adapted  to  perform ;  so  that  the 
crude  masses  of  food  remain  a  heavy  burden  within  the 
stomach,  and  a  source  of  distress  to  that  organ,  retarding 
the  performance  of  its  legitimate  duty.      Hence  persons 
who  habitually  eat  too  rapidly,  frequently  fall  victims  to 
dyspepsia.       Rapid   eating  also   conduces   to    overeating. 
The  food  is  introduced  so  rapidly,  that  the  system  has  not 


19.  Rapid  eating?    Describe  the  process  and  effects. 

20.  Loss  of  taste?     Another  effect  of  rapid  eating?    Mistakes? 

21.  Effect  of  imperfectly  broken  food  in  the  stomach  *    Dyspepsia?     Over- 
eating ? 


DIGESTION. 


time  to  recognize  that  its  real  wants  are  met,  and  that  its 
losses  have  been  made  good;  and  hence  the  appetite  con- 
tinues, although  more  nutriment  has  been  swallowed  than 
the  system  requires,  or  can  healthfully  appropriate. 

22.  The  Stomach. — As  soon  as  each  separate  portion 
of  food  is  masticated  and  insalivated,  it  is  swallowed ;  that 

is,  it  is  propelled  down- 
ward to  the  stomach, 
through  a  narrow  mus- 
cular tube  about  nine 
inches  in  length,  called 
the  ffisopliagux,  or  gul- 
let (Fig.  'S3).  The 
stomach  is  the.  only 
large  expansion  of  the 
digestive  canals  and  is 
the  most  important  or- 
gan of  digestion.  It  is 
a  hollow,  pear-shaped 
pouch,  having  a  ca- 
pacity  of  three  pints, 
in  the  adult.  Its  walls 
are  thin  and  yielding, 
and  may  become  un- 
naturally distended,  as 
in  the  case  of  those 
who  subsist  on  a  bul- 
ky, innutritions  diet, 
and  of  those  who  habitually  gormandize. 

23.  The  stomach  has  also  two  openings;  that  by  which 
food  enters,  being  situated  near  the  heart,  is  called  the 
cardiac,  or   heart    orifice;   the   other  is   the   pylorus,   or 
"  gatekeeper,"  which  guards  the  entrance  to  the  intestines, 


.  22. — SECTION  op  CHEST  AND  ABDOMEN. 

A,  Heart.  D,  The  Liver. 

B,  The  Lungs.  E,  Large  Intestine. 

C,  Stomach.  G,  Small  Intestine. 


22.  Gullet?    Describe  the  stomach  and  its  location.    Effects  of  gormandizins? 

23.  Heart-orifice?     Gatekeeper?    Coins,  etc.?    Indication  of  the    soil   and 
yielding  texture  of  the  stomach  ? 


DIGESTION. 


91 


-c 


and,   under    ordinary   circumstances,   permits   only   such 

matters  to  pass  it  as  have  first  been  properly  acted  upon 

in  the  stomach.    Coins,  buttons,  and  the  like  are,  however. 

readily  allowed  to  pass,  because  they  can  be  of  no  use  if 

retained.     The  soft  and 

yielding  texture  of  this 

organ  —  the    stomach  — 

indicates    that  it  is  r^h 

designed   to   crush    antT 

comminute  solid  articles 

of  food. 

24.  The  Gastric0 
Juice.— We  have  seen 
how  the  presence  of  food 
in  the  mouth  excites  the 
salivary  glands,  causing 
the  saliva  quickly  to 
flow.  In  the  same  man- 
ner, when  food  reaches 
the  stomach,  its  inner 
lining,  the  mucous  mem- 
brane, is  at  once  excited 
to  activity.  (At  first  its 
surface,  which  while  the 
stomach  is  empty  pre- 
sents a  pale  pink  hue, 
turns  to  a  bright  red 
color,  for  the  minute 
blood-vessels  which 
course  through  it,  are  filled  with  blood. )(  Presently  a  clear, 
colorless,  and  acid  fluid  exudes,  drop  by  drop,  from  its  nu- 
merous minute  glands  or  "tubules,"  until  finally  the  surface 
is  moistened  in  every  part,  and  the  fluid  begins  to  mingle 
with  the  food.  This  fluid  is  termed  the  gastric  juice. \ 


FIG.  23.— THE  ORGANS  OF  DIGESTION. 

O,  O3«ophagus.       I,  Small  Intestines. 
S,  Stomach.  C,  Large  Intestines. 

L,  Liver.  P,  Pancreas. 

M,  Pylorus.  N,  Spleen. 

G,  Gall-bladder. 


24.  What  is  meant  by  the  gastric  juice  ? 


92  DIGESTION. 


25.  The  gastric  juice  is  the   proper  solvent  of  certain 
articles  of   food,  especially  those   belonging  to  the  albu- 
minoid class.     This  solvent  power  is  due  to  its  peculiar  in- 
gredient, pepsin ;  in  digestion,  this  substance  acts  like  a 
ferment ;  that  is,  it  induces  changes  in  the  food  simply  by 
its  presence,  but  does  not  itself  undergo  change.    The  acid- 
ity of  the  gastric  juice,  which  is  due  to  lactic  acid,  is  not 
accidental;  for  we  find  that  the  |flpi  cannot  act  in  an 
alkaline  solution — that  is,  one  whicn  is  not  acid  or  neutral. 

fThe  quantity  of  gastric  juice  secreted  daily  is  very  large, 
probably  not  less  than  three  or  four  pints  at  each  meal. 
Though  this  fluid  is  at  once  used  in  the  reduction  of  the 
food,  it  is  not  lost;  since  it  is  soon  re-absorbed  by  the 
stomach,  together  with  those  parts  of  the  food  which  it 
has  digested  and  holds  in  solution.  \ 

26.  Movements  of  the  Stomach. — The  inner  coat- 
ing of  the  stomach  is  the  mucous  membrane,  which,  as  we 
have  seen,  furnishes  the  gastric  juice.     Next  to  this  coating 
lies  another,  called  the  muscular  coat,  composed  of  invol-* 
untary  muscular  fibres,  some  of  which  run  circularly,  and 
others  in  a  longitudinal  direction.     These  expand  to  ac- 
commodate the  food  as  it  is  introduced,  and  contract  as  it 
passes  out,     In  addition,  these  fibres  are  in  continual  mo- 
tion while  food  remains  in  the  stomach,  and  they  act  in 
such  manner  that  the  contents  are  gently  turned  round 
from  side  to  side,   or   from  one  end  of  it  to  the  other. 

27.  By   these   incessant    movements    of   the    stomach, 
called  the  peristaltic  movements,  the  gastric  juice  comes 
in  contact  with  all  parts  of  the  food.     We  are,  however, 
not  conscious  that  these  movements  take  place,  nor  have 
we  the  power  to  control  them.     When  such  portions  of  the 
food  as  are  sufficiently  digested  approach  the  pylorus,  it 

25.  .What  is  the  office  of  the  gastric  juice?    Acidity  of  the  gastric  juice* 
Quantity  of  gastric  juice  used  ?    What  becomes  of  it  ? 

26.  Muscular  coat  of  the  stomach?     Expansion  and  contraction  of  its  fibres? 
Action  of  the  fibres? 

27.  Peristaltic  movements?    What  is  said  of  our  consciousness  of  and  power 
over  these  movements  ?    Describe  the  movements  of  the  pylorus. 


DIGESTION.  93 


expands  to  allow  them  to  pass  out,  and  it  closes  again  to 
confine  the  residue  for  further  preparation. 

28.  The  knowledge  of  these  and  other  interesting  and 
instructive  facts  has  been  obtained  by  actual  observation  ; 
the  workings  of  the  stomach  of  a  living  human  being  have 
been  laid  open  to  view  and  examined — the  result  of  a  re- 
markable accident.   Alexis  St.  Martin,  a  Canadian  voyageur, 
received  a  gun-shot  wound  which  laid  open  his  stomach, 
and  which,  in  healing,  left  a  permanent  orifice  nearly  an 
inch  in  diameter.      Through   this   opening  the  observer 
could  watch  the  progress  of  digestion,  and  experiment  with 
different  articles  of  food.     Since  that  occurrence,  artificial 
openings  into  the  stomach  of  the  inferior  animals  have 
been  repeatedly  made,  so  that  the  facts  of  stomach-digestion 
are  very  well  ascertained  and  verified. 

29.  Gastric  Digestion. — What  portions  of  the  food 
are  digested  in  the  stomach  ?     It  was  formerly  thought 
that  all  the  great  changes  of  digestion  were  wrought  here, 
but  later  investigation  has  taught  us  better.     We  now  know 
that  the  first  change  in  digestion  takes  place  in  the  mouth,  in 
the  partial  conversion  of  starch  into  sugar.     We  also  know 
that,  of  the  three  organic  food  principles  (considered  in 
Chapter  IV.)  two — the  fats  and  the  sugars — are  but  slightly 
affected  by  the  stomach ;  but  that  its  action  is  confined  to 
that  third  and  very  important  class,  from  which  the  tissues 
are   renewed,   the   albuminoids.     A  few  articles  need  no 
preparation  before  entering  the  system,  as  water,  salt,  and 
grape-sugar.     These   are   rapidly  taken  up  by  the  blood- 
vessels  of  the   stomach,   which    everywhere   underlie   its 
mucous  membrane  in  an  intricate  and  most  delicate  net- 
work.    In  this  way  the  function  of  absorption  begins. 

30.  The  albuminoid  substances  are  speedily  attacked  and 


28.  How  has  the  knowledge  and  the  workings  of  the  stomach  been  ascertained  ? 
St.  Martin?     How  else? 

29.  What  was  formerly  thought.  ?    What  do  we  now  know  ?    What  else  do  we 
now  know  ?    Water,  salt,  and  sugar?    Absorption  ? 

30.  Albuminose?    The  process  ?    Chyme? 


94  DIGESTION. 


digested  by  the  gastric  juice.  From  whatever  source  they 
are  derived,  vegetable  or  animal,  they  are  all  transformed 
into  the  same  digestive  product,  called  albuminose.  This  is 
very  soluble  in  water,  and  is  readily  absorbed  by  the  blood- 
vessels of  the  stomach.  After  a  longer  or  shorter  time, 
varying  from  one  to  five  hours,  according  to  the  individual 
and  the.  quantity  and  quality  of  his  food,  the  stomach  will 
be  found  empty.  Xot  only  has  the  digested  food  passed 
out,  but  also  those  substances  which  the  stomach  could 
not  digest  or  absorb  have  passed  little  by  little  through 
the  pylorus,  to  undergo  further  action  in  the  intestines. 
At  the  time  of  its  exit,  the  digested  food  is  of  a  pulpy 
consistence,  and  dark  color,  and  is  then  known  as  the  chyme. 

31.  The    Intestines. — The    intestines,   or    "bowels,"' 
are  continuous  with  the  stomach,  and  consist  of  a  fleshy 
tube,   or   canal,   twenty-five   feet  in   length.     The    small 
intestine,  whose  diameter  is  about  one  inch  and  a  half,  is 
twenty  feet  long  and  very  tortuous.     The  large  intestine  is 
much  wider  than  the  former,  and  five  feet  long  (Fig.  2§). 
The  general  structure  of  these  organs  resembles  that  of  the 
stomach.     Like  it,  they  are  provided  with  a  mucous  mem- 
brane, or  inner  lining,  whence  flow  their  digestive  juices; 
and,  just  outside  of  this,  a  muscular  coat,  which  propels 
the  food  onward  from  one  point  to  another. 

32.  Moreover,  both  the  intestines  and  stomach  are  envel- 
oped in  the  folds  of  the  same  outer  tunic  or  membrane,  called 
the  peritoneum.     This  is  so  smooth  and  so  well  lubricated, 
that  the  intestines  have  the  utmost  freedom  of  motion. 
In  the  small  intestines,  the  work  of  digestion  is  completed, 
the  large  intestine  receiving  from  them  the   indigestible 
residue  of  the  food,  and  in  time  expelling  it  from  the  body. 

33.  Intestinal    Digestion. — As    soon    as    the   food 
passes  the  pylorus  and  begins  to  accumulate  in  the  upper 

31.  What  are  the  intestines?    The  small  intestines?    The  large  intestines? 
Their  structure? 

32.  Peritoneum  ?    The  work  of  digestion  ? 

33.  The  presence  of  food  in  the  intestines  ?  ,Bile  ? 


DIGESTION.  95 


part  of  the  intestines,  it  excites  the  flow  of  a  new  digestive 
fluid,  which  enters  through  a  small  tube,  or  duct,  about 
three  inches  below  the  stomach.  It  is  formed  by  the  union 
of  two  distinct  fluids — the  bile  and  the  pancreatic  juice. 
The  bile  is  secreted  by  the  liver,  which  is  the  largest  gland 
of  the  body,  and  is  situated  on  the  right  side  and  upper 
part  of  the  abdomen  (Fig.  22).  The  bile  is  constantly 
formed,  but  it  flows  most  rapidly  during  digestion.  Dur- 
ing the  intervals  of  digestion  it  is  stored  in  the  gall-bladder ', 
a  small  membranous  bag  attached  to  the  under  side  of  the 
liver.  This  fluid  is  of  a  greenish-yellow  color,  having  a 
peculiar  smell,  and  a  very  bitter  taste. 

34.  The  pancreatic  juice  is  the  product  of  a  gland  called 
$\Q  pancreas,  situated  behind  the  stomach.    This  fluid  is  col- 
orless, viscid,  and  without  odor.     Like  the  digestive  juices 
previously  described,  it  owes  its  solvent  power  to  its  pecu- 
liar ferment  principle,  called  pancreatin.      By  the  joint 
action  of  these  fluids,  the  fatty  parts  of  the  food  are  pre- 
pared for  absorption.     By  previous  steps  of  digestion  the 
fats  are  merely  separated  from  the  other  components  of  the 
food ;  but  here,  within  the  intestines,  they  are  reduced  to  a 
state  of  minute  division,  or  emulsion,  resembling  the  con- 
dition  of  butter  in   milk,  before   it  has   been   churned. 
There  results  from  this  action  a  white  and  milky  fluid, 
termed  the  chyle,  which  holds  in  solution  the  digestible 
portions  of  the  food,  and  is  spread  over  the  extensive 
absorbent  surface  of  the  small  intestines. 

35.  The    mucous    membrane    of   the    intestines,    also, 
secretes  or  produces,  a  digestive  fluid  by  means  of  numer- 
ous "follicles,"  or  minute  glands;  this  is   called  the  in- 
testinal juice.     From  experiments  on  the  inferior  animals, 
it  has  been  ascertained  that  this  fluid  exerts  a  solvent  influ- 
ence over  each  of  the  three  organic  food  principles,  and  in 
tins' way  may  supplement  and  complete  the  action  of  the 

34.  The  pancreatic  juice  ?    The  joint  action  of  these  fluids*  ? 

35.  The  mucous  membrane  ?    Experiments  on  inferior  animals  ? 


96  DIGESTION. 


fluids  previously  mentioned,  viz. : — of  the  saliva  in  convert- 
ing starch  into  sugar,  of  the  gastric  juice  in  digesting  the 
albuminoids,  and  of  the  pancreatic  juice  and  bile  in 
emulsifying  the  fats. 

36.  Absorption. — With  the  elaboration  of  the  chyle, 
the  work  of  digestion  is  completed  ;  but,  in  a  certain  sense, 
the  food  is  yet  outside  of  the  body  ;  that  is,  the  blood  is  not 
yet  enriched  by  it,  and  it  is  not  in  a  position  to  nourish  the 
tissues.    The  process  by  which  the  liquefied  food  passes  out 
of  the  alimentary  canal  into  the  blood  is  called  absorption. 
This  is  accomplished  in  two  ways ;  first,  by  the  blood-vessels. 
We  have  seen  how  the  inner  membrane  of  the  stomach  is 
underlaid  by  a  tracery  of  minute  and  numerous  vessels, 
and  how  softie  portions  of  the  food  are  by  them  absorbed. 
The   supply   of    blood-vessels    to   the   intestines   is   even 
greater;   particularly  to  the  small  intestines,  where  the 
work  of  absorption  is  more  actively  carried  on.  / 

37.  The  absorbing  surface  of  the  small  intestines,  if  con- 
sidered as  a  plane  surface,  amounts  to  not  less  than  half  a 
square  yard.     Besides,  the  mucous  membrane  is  formed  in 
folds  with  an  immense  number  of  thread-like  prolongations, 
called  villi,  which  indefinitely  multiply  its  absorbing  capa- 
city.    These  minute  processes,  the  villi,  give  the  surface 
the  appearance   and   smoothness  of  velvet;    and   during 
digestion,  they  dip  into  the  canal,  and,  by  means  of  their 
blood-vessels,  absorb  its  fluid  contents,  just  as  the  spongi- 
oles  which  terminate  the  rootlets  of  plants,  imbibe  moisture 
from  the  surrounding  soil. 

38.  Secondly,  absorption  is  also  effected  by  the  lacteals,  a 
set  of  vessels  peculiar  to  the  small  intestines.     These  have 
their  beginnings  in  the  little  villi  just  mentioned,  side  by 
side  with  the  blood-vessels.     These  two  sets  of  absorbents 
run  in  different  courses,  but  their  destination  is  the  same, 


36,  37.  How  much  thus  far  has  been  done  with  the  food  ?    The  next  process  ? 
Give  the  first  way. 

38.  How  is  absorption  effected  in  another  way?     Describe  it.     Name  of  the 
"teals  ?    Thoracic  duct  ? 


DIGESTION. 


97 


which  is  the  right  side  of  the  heart.  The  lacteals  receive 
their  name  from  their  milky-white  appearance.  After  a 
meal  containing  a  por- 
tion of  fat,  they  are 
then  distended  with 
chyle,  which  they  are 
specially  adapted  to 
receive:  at  other  times 
they  are  hardly  dis- 
cernible. The  lacteals 
all  unite  to  form  one 
tube,  the  thoracic  duct, 
which  passes  upward 
through  the  thorax,  or 
chest,  and  empties  into 
a  large  vein,  situated 
just  beneath  the  left 
collar-bone. 

39.  The  Absorb- 
ents, —  The    lacteals 
belong  to   a   class  of 

vessels  known  as  absorbents,  or  lymphatics,  which  ram- 
ify in  nearly  all  parts  of  the  body,  except  the  brain  and 
spinal  cord.  The  fluid  which  circulates  through  the  lym- 
phatics of  the  limbs,  and  all  the  organs  not  concerned  in 
digestion,  is  called  lympli.  This  fluid  is  clear  and  color- 
less, like  water,  and  thus  differs  from  the  milky  chyle 
which  the  lacteals  carry  after  digestion  :  it  consists  chiefly 
of  the  watery  part  of  the  blood,  which  was  not  required  by 
the  tissues,  and  is  returned  to  the  blood  by  the  absorbents 
or  lymphatics. 

40.  Circumstances   affecting  Digestion.  —  What 
length  of  time  is  required  for  the  digestion  of  food  ?   From 
observations  made,  in  the  case  of  St.  Martin,  the  Canadian 


FIG.  24. — THE  LACTEALS. 
A,  Small  Intestine.         B,  Lacteals. 
C,  Thoracic  Duct.  D,  Absorbents. 

E,  Blood-vessel. 


39.  The  absorbents  ?    Lymph  ?    What  further  of  tho  lymph  ? 

40.  What  can  you  state  as  to  the  time  required  for  digestion  ? 


98  DIGESTION. 


already  referred  to,  it  has  been  ascertained  that,  at  the  end 
of  two  hours  after  a  meal,  the  stomach  is  ordinarily  empty. 
How  much  time  is  needed  to  complete  the  digestion  of 
food,  within  the  small  intestines,  is  not  certain  ;  but,  from 
what  we  have  learned  respecting  their  functions,  it  must 
be  evident  that  it  largely  depends  upon  the  amount  of 
starch  and  fat  which  the  food  contains. 

41.  In   addition   to   the    preparations   which    the   food 
undergoes  in  cooking,  which  we  have  already  considered, 
many  circumstances  affect  the  duration  of  digestion  ;  such 
as  the  quality,  quantity,  and  temperature  of  the  food ;  the 
condition  of  the  mind  and  body ;  sleep,  exercise,  and  habit. 
Fresh  food,  except  new  bread   and   the  flesh  of  animals 
recently  slain,  is  more  rapidly  digested  than  that  which  is 
stale ;  and  animal  food  more  rapidly  than  that  from  the 
vegetable  kingdom. 

42.  Food  should  not  be  taken  in  too  concentrated  a  form, 
the  action  of  the  stomach  being  favored  when  it  is  some- 
what bulky ;  but  a  large  quantity  in  the  stomach  often  re- 
tards digestion.     If  the  white  of  one  egg  be  given  to  a  dog, 
it  will  be  digested  in  an  hour,  but  if  the  white  of  eight 
eggs  be  given  it  will  not  disappear  in  four  hours.    A  wine- 
glassful  of  ice-water  causes  the  temperature  of  the  stomach 
to  fall  thirty  degrees ;  and  it  requires  a  half-hour  before  it 
will  recover  its  natural  warmth — about  a  hundred  degrees — 
at  which  the  operations  of  digestion  are  best  conducted. 
A  variety  of  articles,  if  not  too  large  in  amount,  is  more 
easily  disposed  of  than  a  meal  made  of  a  single  article; 
although  a  single  indigestible  article  may  interfere  with 
the  reduction  of  articles  that  are  easily  digested. 

43.  Strong  emotion,  whether  of  excitement  or  depression, 
checks  digestion,  as  do  also  a  bad  temper,  anxiety,  long 
fasting,  and  bodily  fatigue.     The  majority  of  these  condi- 


41.  Circumstances  affecting  duration  of  digestion  ?    Fresh  food  ? 

42.  Food  in  concentrated  form  ?    A  large  quantity  of  food?    Experiment  on 
the  dog  ?    Ice-water  ?    Variety  of  articles  ? 

43.  Strong  emotion  ?    The  tongue  of  the  patient  ? 


DIGESTION. 


99 


tions  make  tlie  mouth  dry,  that  is,  they  restrain  the  flow 
of  the  saliva ;  and  without  doubt  they  render  the  stomach 
dry  also,  by  preventing  the  flow  of  the  gastric  juice.  And, 
as  a  general  rule,  we  may  decide,  from  a  parched  and  coated 
tongue,  that  the  condition  of  the  stomach  is  not  very  dis- 
similar, and  that  it  is  unfit  for  the  performance  of  digestive 
labor.  This  is  one  of  the  points  which  the  physician  bears 
in  mind  when  he  examines  the  tongue  of  his  patient. 

44.  The  practice  of  eating  at  short  intervals,  or  "  between 
meals,"  as  it  is  called,  has  its  disadvantage,  as  well  as  rapid 
eating  and  over-eating,  since  it  robs  the  stomach  of  its  needed 
period  of  entire  rest,  and  thus  overtasks  its  power.  With 
the  exception  of  infants  and  the  sick,  no  persons  require 
food  more  frequently  than  once  in  four  hours.  Severe 
exercise  either  directly  before  or  directly  after  eating  retards 
digestion ;  a  period  of  repose  is  most  favorable  to  the  proper 
action  of  the  stomach.  The  natural  inclination  to  rest 
after  a  hearty  meal  may  be  indulged,  but  should  not  be 
carried  to  the  extent  of  sleeping;  since  in  that  state  the 
stomach,  as  well  as  the  brain  and  the  muscles,  seeks  re- 
lease from  labor. 

44.  Eating  between  meals  ?    Severe  exercise  ?    Sleep  after  meals  } 


/   ,4^*^*^-7? 

u//sJe,  &. 


100  REVIEW   QUESTIONS. 


QUESTIONS  FOR  TOPICAL  REVIEW. 

PAGE 

1.  What  do  you  understand  by  nutrition  ? 80 

2.  How  ie  the  process  of  nutrition  carried  on  * 80 

3.  What  further  can  you  state  on  the  subject  ? 80,  81 

4.  Describe  the  general  plan  of  digestion 81 

5.  How  is  the  process  of  mastication  carried  on  ? , 80,  82 

ti.  State  what  you  can  in  relation  to  the  formation  of  the  teeth 82,  86 

7.  What,  in  relation  to  their  arrangement  ? &3,  84 

8.  What,  in  relation  to  the  process  of  "  shedding  ?" 82,  83,  84 

9.  In  relation  to  the  different  forms  of  teeth  in  different  animals  ? fc5 

10.  What  causes  operate  to  injure  or  destroy  the  teeth  ? 85,  86 

11.  What  suggestions  and  directions  are  given  for  the  preservation  of  the 

teeth  ? 85,  86 

12.  What  do  you  understand  by  insalivatiou  ? 80,  86 

13.  How  is  the  process  of  insalivation  carried  on  ': 86,  87,  88 

14.  Of  what  importance  is  the  saliva  to  the  process  ? 87,  88 

15.  Of  what  importance  are  mastication  and  insalivation  ? 88,  89 

16.  Describe  the  consequences  of  rapid  eating 89,  90 

Y7.  What  becomes  of  the  food  directly  after  it  has  undergone  mastication 

and  insalivation  ? 90 

18.  Describe  the  location  and  formation  of  the  stomach 90,  91,  92 

19.  Describe  the  process  by  which  the  gastric  juice  is  formed '.         91 

20.  What  are  the  properties  and  uses  of  the  gastric  juice  ? 92 

21.  What  are  the  movements  of  the  stomach,  and  what  their  uses  ? 92,  93 

22.  What  further  can  you  state  on  the  subject  ? 93 

23.  What  portions  of  the  food  are  digested  in  the  stomach  ? 93,  94 

24.  What  are  the  first  changes  of  digestion  * 93 

25.  Describe  the  location  and  formation  of  the  stomach 94 

26.  What  further  can  you  state  in  relation  to  the  stomach  ? 94 

27.  Descri  be  the  process  of  intestinal  digestion 94,  95,  96 

28.  What  do  you  understand  by  absorption  ? 80,-  96 

29.  How  is  the  process  of  absorption  effected  ? 9(5,  97 

30.  What  are  the  lacteals,  and  of  what  use  are  they  * 96,  97 

31.  What  length  of  time  is  required  for  the  digestion  of  food  ? 97,  98 

32.  What  circumstances,  of  food,  affect  digestion  ? 98 

33.  What  circumstances,  of  emotion,  affect  digestion  ? 98,  99 

S4.  What  suggestions  and  directions  are  given  upon  the  subject  of  eating 

and  drinking  ? 98,  99 


CIRCULATION  OF  TF1E   BLOOD. 
I  H«Arl,Lungs,  Arteries  &  Veins.] 


THE    CIRCULATION  101 


CHAPTER  VII.  • '  •  *  >  5  .  *«  .1 

T-HE     CIRCULATION, 

Tlie  Blood — Its  Plasma  and  Corpuscles — Coagulation  of  the  Blood — The 
Uses  of  the  Blood — Transfusion — Change  of  Color — The  Organs  of 
the  Circulation — The  Heart,  Arteries,  and  Veins — The  Cavities 
and  Valves  of  the  Heart — Its  Vital  Energy — Passage  of  the  Blood 
through  tfie  Heart — The  Frequency  and  Activity  of  its  Movements — 
The  Pulse — The  Spygmograph — The  Capillary  Blood-vessels— T/ie 
Rate  of  the  Circulation — Assimilation — Injuries  to  the  Blood-vessels. 

1.  The  Blood. — Every  living  organism  of  the  higher 
sort,  whether  animal  or  vegetable,  requires  for  the  main- 
tenance of  life  and  activity,  a  circulatory  fluid,  by  which 
nutriment  is  distributed  to  all  its  parts.     In  plants,  this 
fluid  is  the  sap;  in  insects,  it   is  a  watery  and  colorless 
blood;   in  reptiles   and  fishes,   it   is   red  but   cold  blood; 
while  in  the  nobler  animals  and  man,  it  is  the  red  and 
warm  blood. 

2.  The  blood  is  the  most  important,  as  it  is  the  most 
abundant,  fluid  of  the  body ;  and  upon  its  presence,  under 
certain  definite  conditions,  life  depends.     On  this  account 
it  is   frequently,   and  very  properly,   termed   "the  vital 
fluid."     The  importance  of  the  blood,  as  essential  to  life, 
was  recognized  in  the  earliest  writings.     In  the  narration 
of  the  death  of  the  murdered  Abel,  it  is  written,  "the  voice 
of  his  blood  crieth  from  the  ground."     In  the  Mosaic  law, 
proclaimed  over  thirty  centuries  ago,  the  Israelites  were 
forbidden  to  eat  food  that  contained  blood,  for  the  reason 
that  "the  life  of  the   flesh   is  in   the  blood."     With  the 
exception   of  a  few  tissues,  such   as  the   hair,  the   nails, 
and  the  cornea  of  the  eye,  blood  everywhere  pervades  the 
body,  as  may  be  proven  by  puncturing  any  part  with  a 

1.  What  is  required  by  every  living  organism?  In  plants  ?  Insects?   Reptiles*? 
Man? 

2.  Importance  and  abundance  of  blood?    Dependence  of  life  ?    Abel?    Mosaic 
law  ?  In  what  part  of  the  body  is  blood  not  found  ?  Quantity  of  blood  in  the  body  ? 


102 


THE  CIRCULATION: 


Q«edle.  The  total  quantity  of  blood  in  the  body  is  esti- 
mated at  about  one-eighth  of  its  weight,  or  eighteen 
pounds. 

3.  The  color  of  the  blood,  in  man  and  the  higher  ani- 
mals, as  is  well  known,  is  red ;  but  it  varies  from  a  bright 
scarlet  to  a  dark  purple,  according  to  the  part  whence  it  is 
taken.     "  Blood  is  thicker  than  water,"  as  the  adage  truly 
states,  and  has  a  glutinous  quality.     It  has  a  faint  odor, 
resembling  that  peculiar  to  the  animal  from  which  it  is 
taken. 

4.  When  examined  under  the  microscope,  the  blood  no 
longer  appears  a  simple  fluid,  and  its  color  is  no  longer  red. 
It  is  then  seen  to  be  made  up  of  two  distinct  parts:  first, 
a  clear,  colorless  fluid,  called  the  plasma ;  and  secondly, 
of   a  multitude    of   minute    solid   bodies,   or  corpuscles, 
that  float  in  the  watery  plasma.     The  plasma,  or  nutritive 
liquid,  is  composed  of  water  richly  charged  with  materials 
derived   from    the   food,   viz.,  '  albumen,   which    gives   it 
smoothness  and  swift  motion;  fibrin;  certain  fats;  traces 
of  sugar;  and  various  salts. 

5.  The  Blood  Corpus- 
cles.— In  man,  these  remark- 
able "little  bodies,"  as  the 
word  corpuscles  signifies,  are 
of  a  yellow  color,  but  by  their 
vast  numbers  impart  a  red 
hue  to  the  blood.  They  are 
very  small,  having  a  diameter 
of  about  -j^Vo  °f  an  inch,  and 
being  one-fourth  of  that  frac- 
tion in  thickness; 'so  that  if 
3,500  of  them  were  placed  in 
line,  side  by  side,  they  would  only  extend  one  inch;  or,  if 


FIG.  25.— THE  BLOOD  CORPUSCLES. 


3.  Color  of  blood?    Its  consistence  ?    Odor? 

4.  What  is  stated  of  the  blood  an  viewed  under  the  microscope  ? 

5.  State  what  you  can  of  the  little  bodies  called  corpuscles. 


THE   CIRCULATION 


103 


piled  one  above  another,  it  would  take  at  least  14,000  of 
them  to -stand  an  inch  high.  Although  so  small  in  size, 
they  are  very  regular  in  form.  As  seen  under  the  micro- 
scope, they  are  not  globular  or  spherical,  but  flat,  circular, 
and  disc-like,  with  central  depressions  on  each  side,  some- 
what like  a  pearl  button  that  has  not  been  perforated.  In 
freshly-drawn  blood  they  show  a  disposition  to  arrange 
themselves  in  little  rolls  like  coins  (Fig.  25). 

6.  The  size  and  shape  of  the  blood  corpuscles  vary  in 
different  animals,  so  that  it  is  possible  to  discriminate  be- 
tween those  of  man   and  the  lower 

animals  (Fig.  26).     This  is  a  point  of 
considerable     practical    importance.  (jP)    c=> 

For  example,  it  is  sometimes  desir- 
able to  decide  in  a  court  of  justice  <a?  # 
the  source,  whether  from  man  or  an 
inferior  animal,  of  blood  stains  upon 
the  clothing  of  an  accused  person,  or 
upon  some  deadly  weapon.  This  may 
be  done  by  a  microscopical  examina- 
tion of  a  minute/portion  of  the  dried 
stain,  previously  refreshed  by  means 
of  gum-water.  .Certain  celebrated 
cases  are  recorded  in  which  the  guilt 
of  criminals  has  been  established,  and 
they  have  been  condemned  and  pun-  ^pvai  corpusciesof  a  fowl, 
ished  upon  the  evidence  which  sci- 
ence rendered  on  this  single  point, 
the  detecting  of  the  human  from 
other  blood. 

7.  The  character  of  the  blood  of  dead,  extinct,  and  even 
fossil  animals,  such  as  the  mastodon,  has  been  ascertained 
by  obtaining  and  examining  traces  of  it  which  had  been 
shut  up,  perhaps  for  ages,  in  the  circulatory  canals  of  bone. 
A  means  of  detecting  blood  in  minute  quantities  is  found 


FIG.  26. 


6.  The  size  and  shape  of  the  corpuscles  ?    Why  is  the  fact  important  ? 

7.  The  character  of  the  blood  of  dead  animals  ?  Means  of  detecting  such  blood  ? 


104  THE   CIRCULATION. 


in  the  spectroscope,  the  same  instrument  by  which  the 
constitution  of  the  heavenly  bodies  has  been  studied.  If 
a  solution  containing  not  more  than  one-thousandth  part 
of  a  grain  of  the  coloring  matter  of  the  corpuscle,  be  ex- 
amined, this  instrument  will  detect  it. 

8.  The  corpuscles,  just  described,  are  known  as  the  red 
blood  corpuscles.     Besides  these,  and  floating  along  in  the 
same  plasma,  are  the  white  corpuscles.     These  are  fewer 
in  number,  but  larger  and  globular  in  form.      They  are 
colorless,  and  their  motion  is  less  rapid  than  that  of  the 
other  variety.     The  total  number  of  both  varieties  of  these 
little  bodies  in  the  blood  is  enormous.    It  is  calculated  that 
in  a  cubic  inch  of  that  fluid  there  are  eighty-three  mil- 
lions, and  at  least  five  hundred  times  that  number  in  ^he 
whole  body. 

9.  Coagulation. — The  blood,  in  its  natural  condit    n 
in  the  body,  remains  perfectly  fluid;  but^  within  a  fe  r 
minutes  after  its  removal  from  its  proper  vessels,  whether 
by  accident  or  design,  a  change  takes  place.     It  begins  to 
coagulate,  or  assume  a  semi-solid  consistence.    If  allowed 
to  stand,  after  several  hours  it  separates  into  two  distinct 
parts,  one  of  them  being  a  dark  red  jelly,  the  coagulum, 
or  clot,  which  is  heavy  and  sinks:  and  the  other,  a  clear, 
straw-colored  liquid,  called  serum,  which  covers  the  clot. 
This  change  is  dependent  upon  the  presence  in  the  blood 
of  fibrin,  which  possesses  the  property  of  solidifying  under 
certain  circumstances;  one  of  these  circumstances   being 
when  the  blood  is  separated  from  living  tissues.     The  color 
of  the  clot  is  due  to  the  entanglement  of  the  corpuscles 
with  the  fibrin. 

10.  In  this  law  of  the  coagulation  of  the  blood  is  our 
safeguard  against  death  by  haemorrhage,  or  against  undue 
loss  of  blood.     If  coagulation  were  impossible,  the  slight- 

8.  White  corpuscles  ?    Total  number  of  corpuscles  in  the  body  ? 

9.  The  blood  in  its  natural  condition  in  the  body  ?    Describe  the  process  by 
which  the  coagulation  of  blood  takes  place  ? 

1 0.  If  coagulation  were  impossible  ?    How  is  it  in  fact  ? 


THE   CIRCULATION.  105 


est  injury  in  drawing  blood  would  prove  fatal.  Whereas 
now,  in  vastly  the  larger  proportion  of  cases,  bleeding 
ceases  spontaneously,  because  the  blood,  as  it  coagulates, 
stops  the  mouths  of  the  injured  blood-vessels.  In  another 
class  of  cases,  where  larger  vessels  are  cut  or  torn,  it  is 
simply  necessary  to  close  them  by  a  temporary  pressure ; 
for  in  a  few  minutes  the  clot  will  form  and  seal  them  up. 
In  still  more  serious  cases,  where  the  blood-vessel  is  of 
large  size,  the  surgeon  is  obliged  to  tie  a  "  ligature''  about 
it,  and  thus  prevent  the  force  of  the  blood-current  from 
washing  away  the  clots,  which,  forming  within  and  around 
the  vessel,  would  close  it  effectually. 

11.  It  is  worthy  of  remark  that  this  peculiarity  is  early 
implanted  in  the  blood,  even  before  birth,  and  in  advance 
of  any  existing  necessity  for  it;    thus   anticipating  and 
guarding  against  danger.     But  this  is  not  all.     Of  most 
of  the  inferior  animals,  which,  as  compared  with  man,  are 
quite  helpless,*the  blood  coagulates  more  rapidly,  and  in 
the   case    of   the   birds,  almost    instantly.     The   relative 
composition  of  fluid  and  coagulated  blood  may  be  thus 
«*<  ^resented : 

Fluid  Blood.  Coagulated  Blood. 

Plasma;.... Serum Serum 

-Fibrin  -  .... 
Corpuscles Corpuscles ...'-^-..Clot. 

12.  The  Uses  of  the  Blood.— The  blood  is  the  great 
provider  and  purifier  of  the  body.     It  both  carries  new 
materials  to  all  the  tissues,  and  removes  the  worn  out  par- 
ticles of  matter.     This  is  effected  by  the  plasma.     It  both 
conveys  oxygen  and  removes  carbonic  acid.     This  is  done- 
through  the  corpuscles.     Some  singular  experiments  have 

1 1 .  What  is  worthy  of  remark  ?     Coagulation  of  the  blood  of  inferior  animals  ': 
Of  the  blood  of  birds  ? 

12.  The  blood,  as  a  provider  and  purifier?     What  uses  does  the  blood  sub- 
serve ?    Experiments  ?    Transfusion  ? 

5* 


106  THE   CIRCULATION. 


been  tried  to  illustrate  the  life-giving  power  of  the  blood. 
An  animal  that  has  bled  so  freely  as  to  be  at  the  point  of 
dying,  is  promptly  brought  back  to  life  by  an  operation 
called  transfusion,  by  which  fresh  blood  from  a  living 
animal  is  injected  into  the  blood-vessels  of  his  body. 

13.  It  is  related  that  a  dog,  deaf  and  feeble  from  age, 
had  hearing  and  activity  restored  to  him  by  the  introduc- 
tion into  his  veins  of  blood  taken  from  a  young  dog ;  and, 
that  a  horse,  twenty-six  yea"rs  old,  having  received  the  blood 
of  four  lambs  acquired  new  vigor.   And  further,  that  a  dog, 
just  dead  from  an  acute  disease,  was  so  far  revived  by  trans- 
fusion, as  to  be  able  to  stand  and  make  a  few  movements. 

14.  Transfusion  has  been  practised  upon  man.     At  one 
time,  shortly  after  Harvey's  discovery  of  the  "  Circulation 
of  the  Blood,"  it  became  quite  a  fashionable  remedy,  it 
being  thought  possible   by  it  to  cure  all  forms  of  disease, 
and  even  to  make  the  old  young  again.     But  these  claims 
were  soon  found  extravagant,  and  many  unhappy  accidents 
occurred  in  its  practice ;  so  that  being  forbidden  by  govern- 
ment and  interdicted   by  the   Pope,  it  rapidly  fell  into 
disuse.    At  the  present  time,  however,  it  is  sometimes  re- 
sorted to  in  extreme  cases,  when  there  has  been  a  great 
and  rapid  loss  of  blood ;  and  there  are  upon  record  several 
instances  where,  other  means  having  failed,  life  has  been 
restored  or  prolonged  by  the  operation  of  transfusion. 

15.  This  reviving  power  of  the  blood  seems  to  reside  in 
the  corpuscles ;  for  transfusion,  when  attempted  to  be  per- 
formed with  the  serum  alone,  has,  in  every  case,  proved  fruit- 
less.   Now,  though  so  much  depends  upon  the  blood  and 
its  corpuscles,  it  is  a  mistake  to  suppose  that  in  them  alone 
is  the  seat  of  life,  or  that  they  are,  in  an  exclusive  manner, 
alive.    All  the  organs  and  parts  of  the  body  are  mutually 
dependent  one  upon  the  other;  and  the  complete  usefulness 


13.  The  caee  of  the  deaf  and  feeble  dog  ?    Horse  ?    Dead  dog  ? 

14.  Transfusion,  as  a  fashionable  remedy  ?    What  further  of  transfusion  y 

15.  The  seat  of  the  reviving  power  of  the  blood  ?    What  further  is  related 


THE    CIRCULATION.  107 


of  the  blood,  or  of  any  other  part,  flows  out  of  the  har- 
monious action  of  all  the  parts. 

16.  Change  of  Color. — The  blood  undergoes  a  variety 
af  changes  in  its  journey  through  the  system.     As  it  visits 
the  different  organs  it  both  gives  out  and  takes  up  mate- 
rials.   In  one  place  it  is  enriched,  in  another  it  is  impover- 
ished.   By  reason  of  these  alterations  in  its  composition, 
the  blood  also  changes  its  color.     In  one  part  of  the  body 
it  is  bright  red,  or  arterial ;  in  another  it  is  dark  blue,  or 
venous.     In  the  former  case  it  is  pure  and  fit  for  the  sup- 
port of  the  tissues ;  in  the  latter,  it  is  impure  and  charged 
with   effete   materials.     (The   details  of  the  change  from 
dark  to  bright  will  be  given  in  the  chapter  on  Respira- 
tion.) 

17.  Circulation. — The  blood  is   in  constant  motion 
during  life.     From   the  heart,  as  a  centre,  a  current  is 
always  setting  toward  the  different  organs ;  and  from  these 
organs  a  current  is  constantly  returning  to  the  heart.     In 
this  way  a  ceaseless  circular  movement  is  kept  up,  which  is 
called  the  Circulation  of  the  Blood.     This  stream  of  the 
vital  fluid  is  confined  to  certain  fixed  channels,  the  blood- 
vessels.    Those  branching  from  the  heart  are  the  arteries ; 
those  converging  to  it  are  the  veins.     The  true  course  of 
the  blood  was  unknown  before  the  beginning  of  the  seven- 
teenth century.     In  1619  it  was  discovered  by  the  illustri- 
ous William  Harvey.    Like  many  other  great  discoverers, 
he  suffered  persecution  and  loss,  but  unlike  some  of  them, 
he  was  fortunate  enough  to  conquer  and  survive  opposi- 
tion.  He  lived  long  enough  to  see  his  discovery  universally 
accepted,  and  himself  honored  as  a  benefactor  of  mankind. 

18.  The  Heart. — The  heart  is  the  central  engine  of 
the  circulation.      In  this  wonderful  little  organ,  hardly 


1 G.  Changes  in  the  blood  ?    What  further  is  stated  ? 

17.  Motion  of  the  blood?    What  is  meant  by  the  circulation  of  the  blood* 
How  confined  ?    Discovery  made  by  Harvey  ? 

18.  Office  of  the  heart?    Location  of  the  heart ?    Its  beat?    Its  shape?    Pro- 
tection to  the  heart  ?    What  else  i*  t-n\d  in  relation  to  the  heart  ? 


108 


THE   CIRCULATION. 


FIG.  i>7.— THE  ORGANS  OP  CIRCULATION. 


THE   CIRCULATION. 


109 


larger  than  a  man's  fist,  resides  that  sleepless  force  by 
which,  during  the  whole  of  life,  the  current  of  the  blood 
is  kept  in  motion. 
It  is  placed  in  the 
middle  and  front 
part  of  the  chest, 
inclining  to  the  left 
side.  The  heart- 
beat may  be  felt  and 
heard  between  the 
fifth  and  sixth  ribs, 
near  the  breast-bone. 
Theshapeof Ihehenrl 
is  conical,  with  the 
apex  or  point  down- 
ward and  in  front. 
The  base,  which  is 
upward,  is  attached 
so  as  to  hold  it  se- 
curely in  its  place, 
while  the  apex  is 
freely  moveable.  In 

Order     that    loSS    of        FIG.  28.— THE  HEART  AND  LARGE  VESSELS. 

power  from  friction        £  Sht  Vent'icle'      %  A^"™16' 
may  be  obviated,  the  F'  Pulmonary  Artcr*- 

heart  is  enclosed  between  two  layers  of  serous  membrane, 
which  forms  a  kind  of  sac.  This  membrane  is  as  smooth 
as  satin,  and  itself  secretes  a  fluid  in  sufficient  quantities 
to  keep  it  at  all  times  well  lubricated.  The  lining  mem- 
brane of  the  heart,  likewise,  is  extremely  delicate  and 
smooth. 

19.  The  Cavities  of  the  Heart.— The  heart  is  hol- 
low, and  so  partitioned  as  to  contain  four  chambers  or 
cavities;  two  at  the  base,  known  as  the  auricles,  from  a 


19.  Formation  of  the  heart  ?    Right  and  left  heart  ? 


110 


THE   CIRCULATION. 


fancied  resemblance  to  the  ear  of  a  dog,  and  two  at  the 
apex  or  point,  called  ventricles.    An  auricle  and  a  ventricle 

on  the  same  side, 
communicate  with 
each  other,  but  there 
is  no  opening  from 
side  to  side.  It  is 
customary  to  regard 
the  heart  as  a  double 
organ,  and  to  speak 
of  its  division  into 
the  right  and  left 
heart.  For  while 
both  halves  act  to- 
gether in  point  of 
time,  each  half  sus- 
tains an  entirely  dis- 
tinct portion  of  the 
labor  of  the  circu- 
lation. Thus,  the 
right  heart  always 
carries  the  dark  or 
venous  blood,  and  the  left  always  circulates  the  bright  or 
arterial  blood. 

20.  If  we  examine  the  heart,  we  at  once  notice  that 
though  its  various  chambers  have  about  the  same  capacity, 
the  walls  of  the  ventricles  are  thicker  and  stronger  than 
those  of  the  auricles.  This  is  a  wise  provision,  for  it  is  by 
the  powerful  action  of  the  former  that  the  blood  is  forced 
to  the  most  remote  regions  of  the  body.  The  auricles,  on 
the  contrary,  need  much  less  power,  for  they  simply  dis- 
charge their  contents  into  the  cavities  of  the  heart  near  at 
hand  and  below  them — into  the  ventricles. 


FIG.  29.— SECTION  OP  THE  HEART. 


A,  Right  Ventricle 

B,  Left  " 

C,  Right  Auricle. 

D,  Left  Auricle. 


E,  F,  Inlets  to  the  Ventricles. 
G,  Pulmonary  Artery. 
H,  Aorta. 


20.  Capacity  of  the  chambers  of  the  heart  ?    What  wise  provision  is  men- 
tioned ?    The  auricles  ? 


THE   CIRCULATION.  Ill 


21.  Action  of  the   Heart.— The  substance  of  the 
heart  is  of  a  deep  red  color,  and  its  fibres  resemble  those 
of  the  voluntary  muscles  by  which  we  move  our  bodies. 
But  the  heart's  movements  are  entirely  involuntary.     The 
advantage   of  this   is   evident;   for  if  it   depended  upon 
us  to  will  each  movement,  our  entire  attention  would  be 
thus  engaged,  and  we  would  find  no  time  for  study,  pleas- 
ure, or  even  sleep.     The  action  of  the  heart  consists  in 
alternate   contractions-  and  dilatations.     During  contrac- 
tion the  walls  come  forcibly  together,  and  thus  drive  out 
the  blood.    In  dilatation,  they  expand  and  receive  a  renewed 
supply.    These  movements  are  called  systole  and  diastole. 
The  latter  may  be  called  the  heart's  period  of  repose ;  and 
although  it  lasts  only  during  two-fifths  of  a  heart-beat,  or 
about  a  third  of  a  second,  yet  during  the  day  it  amounts 
to  more  than  nine  hours  of  total  rest. 

22.  A  remarkable  property  of  the  tissue  of  the  heart  is 
its  intense  vitality.     For  while  it  is  more  constantly  active 
than  any  other  organ  of  the  body,  it  is  the  last  to  part 
with  its  vital  energy.      This  is  especially  interesting  in 
view  of  the  fact  that  after  life  is  apparently  extinguished, 
as  from  drowning,  or  poisoning  by  chloroform,  there  yet 
lingers  a  spark  of  vitality  in  the  heart,  which,  by  contin- 
ued effort,  may  be  fanned  into  a  flame  so  as  to  revivify  the 
whole  body.     In  cold-blooded  animals  this  irritability  of 
the  heart  is  especially  remarkable.     The  heart  of  a  turtle 
will  pulsate,  and  the  blood  circulate  for  .a  week  after  its 
head  has  been  cut  off;  and  the  heart  will  throb  regularly 
many  hours  after  being  cut  out  from  the  creature's  chest. 
The  heart  of  a  frog  or  serpent,  separated  entirely  from  the 
body,  will  contract  at  the  end  of  ten  or  twelve  hours:  that 
of  an  alligator  has  been  known  to  beat  twenty-eight  hours 
after  the  death  of  the  animal. 

21.  Substance  of  the  heart?     Its  fibres?    Its  movements?    The  advantage 
of  such  movements  ?    Action  of  the  heart  ?     Its  period  of  repose  ? 

22.  Remarkable  property  of  the  tissue  of  the  heart  ?    How  shown  ?    How  in- 
teresting?   In  cold-blooded  animals  ?    Heart  of  a  turtle  ?    Of  a  frog?    Alligator? 


THE   CIRCULATION. 


23.  Passage  of  the  Blood  through  the  Heart.— 

Let  us  now  trace  the  course  of  the  blood  through  the 
several  cavities  of  the  heart.  In  the  first  place,  the  venous 
blood,  rendered  dark  and  impure  by  contact  with  the 
changing  tissues  of  the  body,  returns  to  the  right  heart 
by  the  veins.  It  enters  and  fills  the  right  auricle  during 
its  dilatation :  the  auricle  then  contracts  and  fills  the  right 
ventricle.  Almost  instantly,  the  ventricle  contracts  forcibly 
and  hurries  the  blood  along  the  great  artery  of  the  lungs, 
to  be  purified  in  those  organs.  Secondly,  having  completed 
the  circuit  of  the  lungs,  the  pure  and  bright  arterial  blood 
enters  the  left  auricle.  This  now  contracts  and  fills  the  left 
ventricle,  which  cavity,  in  its  turn,  contracts  and  sends  the 
blood  forth  on  its  journey  again  through  the  system.  This 
general  direction  from  right  to  left  is  the  uniform  and  un- 
deviating  course  of  heart-currents. 

24.  The  mechanism  which  enforces  and  regulates  it,  is 
as  simple  as  it  is  beautiful.     Each  ventricle  has  two  open- 
ings, an  inlet  and  an  outlet,  each  of  which  is  guarded  by 
strong  curtains,  or  valves.      These  valves  open  freely  to 
admit  the  blood  entering  from  the  right,  but  close  inflex- 
ibly against  its  return.     Thus,  when  the  auricle  contracts, 
the  inlet  valve  opens ;  but  as  soon  as  the  ventricle  begins 
to  contract,  it  closes  promptly.     The  contents  are  then,  so 
to  speak,  cornered,  and  have  but  one  avenue  of  escape, 
that  through  the  outlet  valve  into  the  arteries  beyond.    As 
soon   as  the  ventricle  begins   to  dilate  again,  this  valve 
shuts  tightly  and  obstructs  the  passage.     The  closing  of 
these  valves  occasions  the  two  heart-sounds,  which  we  hear 
at  the  front  of  the  chest. 

25.  Frequency  of  the  Heart's  Action.— The  alter- 
nation of  contraction  and  dilation  constitutes  the  heart- 


23.  Course  of  the  blood  through  the  heart  ?    Course  of  heart-currents  ? 

24.  Openings  of  the  ventricles  ?    How  guarded  ?    How  do  the  valves  operate  ? 
The  consequence  ?    Heart-sounds  ? 

25.  Heart-beats?    The  heart  as  a  susceptible  organ?    Heat,   exercise,  etc..' 
Posture  ? 


THE    CIRCULATION.  113 


beats.  These  follow  each  other  not  only  with  great 
regularity,  but  with  great  rapidity.  The  average  number 
in  an  adult  man  is  about  seventy-two  in  a  minute.  But 
the  heart  is  a  susceptible  organ,  and  many  circumstances 
affect  its  rate  of  action.  Heat,  exercise,  and  food  will 
increase  its  action,  as  cold,  fasting,  and  sleep  will  decrease 
it.  Posture,  too,  has  a  curious  influence;  for  if  while  sit- 
ting, the  beats  of  the  heart  number  seventy-one;  standing 
erect  will  increase  them  to  eighty-one,  and  lying  down 
will  lower  them  to  sixty-six. 

26.  The  modifying  influence  of  mental  emotions  is  very 
powerful.     Sudden   excitement  of  feeling  will   cause   the 
heart  to  palpitate,  or  throb  violently.    Depressing  emotions 
sometimes  temporarily  interrupt  its  movements,  and  the 
person  faints  in  consequence.     Excessive  joy,  grief,  or  fear, 
lias  occasionally  suspended  the  heart's  action  entirely,  and 
thus  caused  death.     The  rate   of  the  heart-beat  may  be 
naturally  above  or  below  seventy-two.     Thus  it  is  stated 
that  the  pulse  of  the  savage  is  always  slower  than  that  of 
the  civilized  man.     Bonaparte  and  Wellington  were  very 
much  alike  in  their  heart's  pulsations,  which  were  less  than 
fifty  in  the  case  of  each. 

27.  Activity  of  the  Heart. — The  average  number  of 
heart-beats  during  a  lifetime  may  be  considered  as  at  the 
rate  of  seventy-two  per  minute,  although  this  estimate  is 
probably  low  ;  for  during  several  years  of  early  life  the  rate 
is  above  one  hundred  a  minute.     In  one  hour,  then,  the 
heart  pulsates  four  thousand  times ;  in  a  day,  one  hundred 
thousand  times ;  and  in  a  year,  nearly  thirty-eight  million 
times.    If  we  compute  the  number  during  a  lifetime,  thirty- 
nine  years  being  the  present  average  longevity  of  civilized 
mankind,  we  obtain  as  the  vast  aggregate,  fourteen  hun- 
dred millions  of  pulsations. 


26.  Mental  emotions  ?     Sudden  excitement  ?    Excessive  joy  ?    The  heart-beat 
rate  ?    Bonaparte  and  Wellington  ? 

27.  Average  number  of  heart-bears?    In  one  hour  ?    Year?    Lifetime? 


114  THE    CIRCULATION. 


28.  Again,  if  we  estimate  the  amount  of  blood  expelled 
by  each  contraction  of  the  ventricles,  at  four  ounces,  then 
the  weight  of  the  blood  moved  during  one  minute  will 
amount  to  eighteen  pounds.     In  a  day  it  will  be  about 
twelve  tons;  in  a  year,  four  thousand  tons;  and  in  the 
course  of  a  lifetime,  over  one  hundred  and  fifty  thousand 
tons.     These  large  figures  indicate,  in  some  measure,  the 
immense  labor  necessary  to  carry  on  the  interior  and  vital 
operations  of  our  bodies.     In  this  connection,  we  call  to 
mind  the  fanciful  theories  of  the  ancients  in  reference  to 
the  uses  of  the  heart.     They  regarded  it  as  the  abode  of 
the  soul,  and  the  source  of  the  nobler  emotions — bravery, 
generosity,   mercy,   and  love.      The   words    courage   and 
cordiality  are  derived  from  a  Latin  word  signifying  heart. 
Many  other  words  and  phrases,  as  hearty,  heart-felt,  to  learn 
by  heart,  and  large-hearted,  show  how  tenaciously  these  ex- 
ploded opinions  have  fastened  themselves  upon  our  language. 

29.  At  the  present  time  the  tendency  is  to  ascribe  purely 
mechanical   functions  to  the  heart.     This  view,  like  the 
older  one,  is  inadequate;  for  it  expresses  only  a  small  part 
of  our  knowledge  of  this  organ.     The  heart  is  unlike  a 
simple  machine,  because  its  motive  power  is  not  applied 
from  without,  but  resides  in  its  own  substance.     Moreover, 
it  repairs  its  own  waste,  it  lubricates  its  own  action,  and  it 
modifies  its  movements  according  to  the  varying  needs  of 
the  system.     It  is  more  than  a  mere  force-pump,  just  as 
the  stomach  is  something  more  than  a  crucible,  and  the 
eye  something  more  than  an  optical  instrument. 

30.  The  Arteries. — The  tube-like  canals  which  carry 
the  blood  away  from  the  heart   are   the  arteries.     Their 
walls  are  made  of  tough,  fibrous  materials,  so  that  they 
sustain  the  mighty  impulse  of  the  heart,  and  are  not  rup- 
tured.    In  common  with  the  heart,  the  arteries  have  a  del- 


28.  Amount  of  blood  expelled  ?    Theories  of  the  ancients  ? 

29.  The  tendency  at  the  present  time  ?    Why  is  this  view  inadequate  ''. 

30.  What  arc  the  arteries  ?    Their  walls?    Their  membraae  I 


THE   CIRCULATION.  115 


icately  smooth  lining  membrane.  They  are  also  elastic, 
and  thus  re-enforce  the  action  of  the  heart :  they  always 
remain  open  when  cut  across,  and  after  death  are  always 
found  empty. 

31.  The  early  anatomists  observed  this  phenomenon, 
and  supposing  that  the  same  condition  existed  during  life, 
came  to  the  conclusion  that  these  tubes  were  designed  to 
act  as  air-vessels,  hence  the  name  artery,  from  a  Greek 
word  which  signifies  containing  air.     This  circumstance 
aifords  us  an  illustration  of  the  confused  notions  of  the 
ancients  in  reference  to   the  internal   operations   of  the 
body.     Cicero   speaks  of  the   arteries   as  "conveying  the 
breath  to  all  parts  of  the  body," 

32.  The  arterial   system   springs  from  the  heart  by  a 
single  trunk,  like  a  minute  and  hollow  tree,  with  number- 
less branches.     As  these  branches  leave  the   heart  they 
divide   and   subdivide,   continually   growing  smaller  and 
smaller,   until   they   can   no   longer   be   traced   with   the 
naked  eye.     If,  then,  we  continue  the  examination  by  the 
aid  of  a  microscope,  we  see  these  small  branches  sending- 
off  still  smaller  ones,  until  all  the  organs  of  the  body  are 
penetrated  by  arteries. 

33.. The  Pulse. — With  each  contraction  of  the  left 
heart,  the  impulse  causes  a  wave-like  motion  to  traverse 
the  entire  arterial  system.  If  the  arteries  were  exposed  to 
view,  we  might  see  successive  undulations  speeding  from 
the  heart  to  the  smallest  of  the  branches,  in  about  one- 
sixth  part  of  a  second.  The  general  course  of  the  arteries 
is  as  far  as  possible  from  the  surface.  This  arrangement 
is  certainly  wise,  as  it  renders  them  less  liable  to  injury, 
the  wounding  of  an  artery  being  especially  dangerous.  It 
also  protects  the  arteries  from  external  and  unequal  pres- 
sure, by  which  the  force  of  the  heart  would  be  counter* 

3 1 .  Early  anatomist*  ?    The  service  of  the  illustration  ? 

32.  The  arterial  system  ?    The  branches  and  sub-branches  of  the  arteries  ? 

33.  Successive  undulations  from  the  heart  ?    Course  of  the  arteries  *    Protec 
tion  of  the  arteries  ?     General  location  of  the  arteries  ? 


116'  THE    CIRCULATION. 


acted  and  wasted.  Accordingly,  we  generally  find  these 
vessels  hugging  close  to  the  bones,  or  hiding  behind  the 
muscles  and  within  the  cavities  of  the  body. 

34.  In  a  few  situations,  however,  the  arteries  lie  near  the 
surface ;  and  if  we  apply  the  finger  to  any  of  these  parts, 
we  will  distinctly  feel  the  movement  described, taking  place 
in  harmony  with  the  heart-beat.    This  is  part  of  the  wave- 
motion  just  mentioned,  and  is  known  as  the  pulse.     All 
are  more  familiar  with  the  pulse  at  the  wrist,  in  the  radial 
artery ;  but  the  pulse  is  not  peculiar  to  that  position,  for  it 
may  be  felt  in  the  carotid  of  the  neck,  in  the  temporal  at 
the  temple,  and  elsewhere,  especially  near  the  joints. 

35.  Since   the   heart-beat    makes   the  pulse,   whatever 
affects  the  former  affects  the  latter  also.     Accordingly,  the 
pulse  is  a  good  index  of  the  state  of  the  health,  so  far  as 
.the  health  depends  upon  the  action  of  the  heart.     It  in- 
forms the  physician  of  the  condition  of  the  circulation  in 
four  particulars:  its  rate,  regularity,  force,  and  fullness; 
and  nearly  every  disease  modifies  in  some  respect  the  con- 
dition of  the  pulse.     A  very  ingenious  instrument,  known 
as  the  sphygmograph,  or  pulse-writer,  has  recently  been 
invented,  by  the  aid  of  which  the  pulse  is  made  to  write 
upon  paper  its  own  signature,  or  rather  to  sketch  its  own 
profile.     This  instrument  shows  with  great  accuracy  the 


FIG.  30.— THE  FORM  OF  THE  PULSE. 

difference  between  the  pulses  of  health  and  those  of  disease. 
In  Fig.  30  is  traced  the  form  of  the  pulse  in  health,  which 
should  be  read  from  left  to  right.  That  part  of  the  trace 

3  i.  Where  do  the  arteries  lie  ?    If  we  apply  the  finger  *     Pulse  ?    Where  felt  ? 
35.  The  pulse  as  an  index  *   Of  what  does  it  inform  the  physician  ?   Instrument 
for  recording  pulsation  t 


THE   CIRCULATION.  11 


which  is  nearly  perpendicular  coincides  with  the  contrac- 
tion of  the  ventricles ;  while  the  wavy  portion  marks  their 
dilatation. 

36.  The  Veins. — The  vessels  which  convey  the  blood 
on  its  return  to  the  heart  are  the  veins.     They  begin  in 
the  several  organs  of  the  body,  and  at  first  are  extremely 
small;   but  uniting  together  as  they  advance,  they  con- 
stantly increase  in  size,  reminding  us  of  the  way  in  which 
the  fine  rootlets  of  the  plant  join  together  to  form  the 
large  roots,  or  of  the  rills  and  rivulets  that  flow  together 
to  form  the  large  streams  and  rivers.     In  structure,  the 
veins  resemble  the  arteries,  but  their  walls  are  compara- 
tively inelastic.     They  are  more  numerous,  and  commu- 
nicate with  each  other  freely  in  their  course,  by  means  of 
interlacing  branches. 

37.  But  the  chief  point  of  distinction  is  in  the  presence 
of  the  valves  in  the  veins.     These  are  little  folds  of  mem- 
brane, disposed  in  such  a  way,  that 

they  only  open  to  receive  blood 
flowing  toward  the  heart,  and  close 
against  a  current  in  the  opposite 
direction.  Their  position  in  the 
veins  on  the  back  of  the  hand  may 

be  readily  observed,  if  we  first  ob-pio  3(  _THF  VALVBR  op  THE 
struct  the  return  of  blood  by  a  cord  VEINS. 

tied  around  the  forearm  or  wrist.  In  a  few  minutes  the 
veins  will  appear  swollen,  and  upon  them  will  be  seen 
certain  prominences,  about  an  inch  apart.  These  latter 
indicate  the  location  of  the  valves,  or,  rather,  they  show 
.that  the  vessels  in  front  of  the  valves  are  distended  by  the 
blood,  which  cannot  force  a  passage  back  through  them. 

38.  This  simple  experiment  proves  that  the  true  direction 
of  the  venous  blood  is  toward  the  heart.     That  the  color 

36.  What  are  the  vein*  ?    How  do  they  form  ?    What  do  they  resemble  ? 

37.  Valves  in  the  veins  ?    What  are  they  ?    Their  position  ?    Experiment  with 
the  cord  ? 

38.  What  will  be  proved  by  the  experiment  ?    What  inference  is  drawn  ? 


118  THE    CIRCULATION. 


of  the  blood  is  dark,  will  be  evident,  if  we  compare  the 
hand  thus  bound  by  a  cord  with  the  hand  not  so  bound. 
It  also  proves  that  the  veins  lie  superficially,  while  the 
arteries  are  beneath  the  muscles,  well  protected  from  pres- 
sure ;  and  that  free  communication  exists  from  one  vein  to 
another.  If  now  we  test  the  temperature  of  the  constricted 
member  by  means  of  a  thermometer,  we  will  find  that  it  is 
colder  than  natural,  although  the  amount  of  blood  is 
larger  than  usual.  From  this  fact  we  infer,  that  whatever 
impedes  the  venous  circulation  tends  to  diminish  vitality ; 
and  hence,  articles  of  clothing  or  constrained  postures, 
that  confine  the  body  or  limbs,  and  hinder  the  circulation 
of  the  blood,  are  to  be  avoided  as  injurious  to  the  health. 

39.  The  Capillaries. — A  third  set  of  vessels  completes 
the  list  of  the  organs  of  the  circulation,  namely,  the  capil- 
lary vessels,   so   called  (from   the  Latin  word  capillarix, 
hair-like),  because  of  their  extreme  fineness.     They  are, 
however,  smaller  than  any  hair,  having  a  diameter  of  about 
Tntair  °f  an  inch,  and  can  only  be  observed  by  the  use  of  the 
microscope.    These  vessels  may  be  regarded  as  the  connect- 
ing link  between  the  last  of  the  arteries  and  the  first  of 
the  veins.     The  existence  of  these  vessels  was  unknown  to 
Harvey,  and  was  the  one  step  wanting  to  complete  his 
great  work.     The   capillaries   were   not   discovered   until 
1661,  a  short  time  after  the  invention  of  the  microscope. 

40.  The  circulation   of  the   blood,  as   seen   under  the 
microscope,  in  the  transparent  web  of  a  frog's  foot,  is  a 
spectacle  of  rare  beauty,  possessing  more  than  ordinary 
interest,  when  we  consider  that   something  very  similar 
is  taking  place  in  our  own  bodies,  on  a  most  magnificent, 
scale.     It  is  like  opening  a  secret  page  in  the  history  of 
our  own  frames.     We  there  see  distinctly  the  three  classes 
of  vessels  with  their  moving  contents;   first,  the  artery, 


39.  Capillaries?    How  regarded  ?    Harvey? 

40.  The  circulation  of  the  blood  in  the  web  of  a  frog's  foot?    Describe  it. 
How  general  is  the  existence  of  the  tissues  t 


THE   CIRCULATION". 


119 


with  its  torrent  of  blood  rushing  down  from  the  heart, 
secondly,  the  vein,  with  its  slow,  steady  stream  flowing  in 
the  opposite  direction ;  and  between  them  lies  the  network 
of  capillaries,  so  fine  that  the  corpuscles  can  only  pass 
through  "in  single  file."  The  current  has  here  an  uncer- 
tain or  swaying  motion,  hurrying  first  in  one  direction,  then 
hesitating,  and  then  turning  back  in  the  opposite  direction, 


FIG.  ;«.— WEB  op  A  FROG'S  FOOT,      FIG.  .33.— MARGIN  OP  FROG'S  W 
slightly  magnified.  magnified  30  diameters. 

and  sometimes  the  capillaries  contract  so  as  to  be  entirely 
empty.  Certain  of  the  tissues  are  destitute  of  capillaries ; 
such  are  cartilage,  hair,  and  a  few  others  on  the  exterior  of 
the  body.  In  all  other  structures,  networks  of  these  vessels 
are  spread  out  in  countless  numbers :  so  abundant  is  the 
supply,  that  it  is  almost  impossible  to  puncture  any  part 
with  the  point  of  a  needle  without  lacerating  tens,  or  even 
hundreds  of  these  vessels. 

41.  The  capillaries  are  elastic,  and  may  so  expand  as  to 
produce  an  effect  visible  to  the  naked  eye.  If  a  grain  of 
sand,  or  some  other  foreign  particle,  lodge  in  the  eye,  it  will 
become  irritated,  and  in  a  short  time  the  white  of  the  eye 
will  be  "blood-shot."  This  appearance  is  due  to  an  in- 

41.  Elasticity  of  the  capillaries?    Grain  of  sand  in  the  eye?    Blush?    Other 
cases  ? 


T20  THE    CIRCULATION. 


crease  in  the  size  of  these  vessels.  A  blush  is  another  exam- 
ple of  this,  but  the  excitement  comes  through  the  nervous 
system,  and  the  cause  is  some  transient  emotion,  either  of 
pleasure  or  pain.  Another  example  is  sometimes  seen  in 
purplish  faces  of  men  addicted  to  drinking  brandy ;  in 
them  the  condition  is  a  congestion  of  the  capillary  circula- 
tion, and  is  permanent,  the  vessels  having  lost  their  power 
of  elastic  contraction. 

42.  Rapidity  of  the  Circulation. — That  the  blood 
moves  with  great  rapidity  is  evident  from  the  almost  instant 
effects   of   certain    poisons,   as    prussic  acid,    which   act 
through  the  blood.     Experiments  upon  the   horse,  dog, 
and  other  inferior  animals,  have  been  made  to  measure 
its  velocity.     If  a  substance,  which  is  capable  of  a  distinct 
chemical  reaction  (as  potassium  ferrocyanide,  or  barium 
nitrate),  be  introduced  into  a  vein  of  a  horse  on  one  side, 
and  blood  be  taken  from  a  distant  vein  on  the  other  side, 
its  presence  may  be  detected  at  the  end  of  twenty  or  thirty- 
two  seconds.     In  man,  the  blood  moves  with  greater  speed, 
and  the  circuit  is  completed  in  twenty-four  seconds. 

43.  What  length  of  time  is  required  for  all  the  blood  of 
the  body  to  make  a  complete  round  of  the  circulation? 
This  question  cannot  be  answered  with  absolute  accuracy, 
since  the   amount  of  the   blood  is   subject  to  continual 
variations.     But,  if  we  assume  this  to  be  one-eighth  of  the 
weight  of  the  body,  about  eighteen  pounds,  it  will  be  suf- 
ficiently correct  for  our  purpose.     Now  to   complete  the 
circuit,  this  blood  must  pass  once  through  the  left  ventricle, 
the  capacity  of  which  is  two  ounces.    Accordingly,  we  find 
that,  under  ordinary  circumstances,  all  the  blood  makes  one 
complete  rotation  every  two  minutes;  passing  successively 
through  the  heart,  the  capillaries  of  the  lungs,  the  arteries, 
the  capillaries  of  the  extremities,  and  through  the  veins. 

42.  Show  what  time  is  required  for  a  given  portion  of  blood  to  travel  once 
around  the  body. 

43.  Time  required  for  all  the  blood  to  circulate  completely  around? 


THE   CIRCULATION. 


44.  Assimilation.  —  The  crowning  act  of  the  circula- 
tion, the  furnishing  of  supplies  to  the  different  parts  of 
the  body,  is  effected  by  means  of  the  capillaries.     The  or- 
gans have  been  wasted  by  use ;  the  blood  has  been  enriched, 
by  the  products  of  digestion.     Here,  within  the  meshes  of 
the  capillary  network,  the  needy  tissues  and  the  needed 
nutriment   are   brought    together.     By   some    mysterious 
chemistry,   each   tissue   selects   and  withdraws   from   the 
blood  the  materials  it  requires,  and  converts  them  into  a 
substance  like  itself.     This  conversion  of  lifeless  food  into 
living  tissue  is  called  assimilation.     The  process  probably 
takes  place  at  all  times,  but  the  period  especially  favorable 
for  it  is  during  sleep.     Then  the  circulation  is  slower,  and 
more  regular,  and  most  of  the  functions  are  at  rest.     The 
body  is  then  like  some  trusty  ship,  which  after  a  long  voy- 
age is  "hauled  up  for  repairs." 

45.  Iiyuries  to  the  Blood-vessels. — It  is  important 
to  be  able  to  discriminate  between  an  artery  and  a  vein,  in 
the  case  of  a  wound,  and  if  we  remember  the  physiology 
of  the  circulation  we  may  readily  do  so.     For,  as  we  have 
already  seen,  haemorrhage  from  an  artery  is  much  more 
dangerous  than  that  from  a  vein.    The  latter  tends  to  cease 
spontaneously  after  a  short  time.     The  arterial  blood  flows 
away  from  the  heart  with  considerable  force,  in  jets;  its 
color  being  bright  scarlet.     The  venous  blood  flows  toward 
the  heart  from  that  side  of  the  wound  furthest  from  the 
heart;  its  stream  being  continuous  and  sluggish;  its  color 
dark.     In  an  injury  to  an  artery,  pressure  should  be  made 
between  the  heart  and  the  wound ;  and  in  the  case  of  a 
vein  that  persistently  bleeds,  it  should  be  made  upon  the 
vessel  beyond  its  point  of  injury. 


44.  What  is  meant  by  assimilation  ?   What  can  you  say  of  its  use,  etc.  ?    Time  ? 

45.  What  is  stated  of  the  injuries  to  the  blood-vessels  ? 


REVIEW   QUESTION'S. 


QUESTIONS  FOR  TOPICAL  REVIEW. 

PAGE 

1.  In  what  organisms  is  the  so-called  circulatory  fluid  found  ?  ...............  101 

2.  How  is  it  designated  in  the  different  organisms  ?  ..........................  101 

3.  What  can  you  state  of  the  importance  of  blood  to  the  body  ?  ..........  101,  105 

4.  Of  its  great  abundance,  color,  and  composition  ?  ..................  101,  102,  107 

5.  Describe  the  corpuscles  of  the  human  blood  ...............   ......  102,  103,  104 

6.  What  is  said  of  them  in  comparison  with  those  of  the  lower  animals  ?.   .  .  103 

7.  Of  the  importance  of  sometimes  detecting  human  from  other  blood  ?  ......  10-3 

8.  What  means  have  we  of  detecting  blood  in  spots  or  stains  ?  ...........  103,  104 

9.  What  is  meant  by  coagulation  of  the  blood  ?  ...............................  104 

10.  What  wisdom  is  there  in  the  law  of  the  blood's  coagulation  5-  .........  104  105 

11.  How  is  this  wisdom  made  manifest  ?  ......................................  105 

12.  In  what  cases  is  the  aid  of  the  surgeon  required  ?  .........................  105 

13.  What  are  the  two  g:  eat  uses  of  the  blood  ?  .................................  105 

14.  Through  what  mediums  is  the  blood  provided  with  new  material  and  re- 

lieved of  the  old  material  ?  ..............................................  105 

15.  What  do  you  understand  by  the  operation  called  transfusion  ?  ...........  106 

16.  What  cases  of  transfusion  are  reported  of  the  lower  animals  ?  .............  100 

17.  What  can  you  state  of  transfusion  as  practised  upon  man  ?  ................  106 

18.  What  further  can  you  say  on  the  subject  ?  .............................  106,  107 

19.  What  changes  take  place  in  the  color  of  the  blood  in  its  journey  through 

the  system  ?  ..................................  .  ..........................  107 

20.  State  all  you  can  in  relation  to  the  circulation  of  the  blood  ................  107 

21.  All,  in  relation  to  the  size,  shape,  and  location  of  the  heart  ...........  107,  109 

22.  How  is  the  loss  of  power  in  the  heart  movements  obviated  ?  .......     ......  109 

23.  Give  a  description  of  the  formation  of  the  heart  ..........  ,  .......  109,  110,  111 

21.  What  can  you  state  of  the  ventricles  and  auricles  of  the  heart  ?  ............  110 

25.  Describe  the  action  of  the  heart  ................  .  ..........................  Ill 

26.  What  special  vitality  does  the  tissue  of  the  heart  possess  ?  .................  Ill 

27.  State  all  you  can  on  the  subject  ...........................................  Ill 

28.  Describe  the  course  of  the  blood  through  the  cavities  of  the  heart  .........  112 

29.  Describe  the  mechanism  that  regulates  the  heart-currents  ........  .  .......  112 

30.  How  do  you  account  for  the  two  heart-sounds  at  the  front  of  the  chest  ?.  .  .  112 

31.  State  what  you  can  of  the  frequency  of  the  heart's  action  .............  112,  113 

32.  Of  the  activity  of  the  heart  ..........................................  113,  114 

33.  What  do  you  understand  by  the  arteries  ?  ............................  114,  115 

34.  State  what  you  can  of  the  arteries  and  the  arterial  system  .............  114,  115 

35.  What  do  you  understand  by  the  pulse  ?  ................................  115,  116 

30.  In  what  part  of  the  body  may  the  pulse  be  felt  ?  ..........................  116 

37.  What  further  can  you  state  of  the  pulse  ?  ..............................  116,  117 

SS.  What  are  the  veins  ?  ......................................................  117 

39.  Where  do  they  exist,  and  how  arc  they  formed  ?  ...........................  117 

40.  Describe  the  valves  of  the  veins  and  their  uses  ............................  117 

41.  Now  give  a  full  description  of  the  construction  of  the  veins  ...............  117 

42.  What  further  can  you  siate  of  the  veins?  ..............................  117,  119 

-13.  What  do  you  understand  by  the  capillaries  ?  ..........................  118,  119 

44    What  service  do  the  capillaries  perform  ?  ........................  118,  110,  121 

45.  Describe  the  circulation  of  the  blood  in  the  region  of  the  heart  .......  118,  119 

46.  What  can  you  state  of  the  rapidity  of  the  blood's  circulation  ?  .............  120 

47.  Of  the  process  known  as  assimilation  ?  ...................................  121 

48.  Of  injuries  to  the  blood-vessels  *  ........   ...............................     121 


RESPIRATION.  123 


CHAPTER    VIII. 
RESPIRATION. 

The  Objects  of  Respiration — The  Lungs — The  Air-Passages — The  Move- 
ments of  Respiration — Expiration,  and  Inspiration — The  Frequency 
of  Respiration — Capacity  of  the  Lungs — The  Air  we  breathe — 
Changes  in  the  Air  from  Respiration — Changes  in  the  Blood — In- 
terchange of  Oases  in  the  Lungs — Comparison  between  Arterial  and 
Venous  Blood — Respiratory  Labor — Impurities  of  the  Air — Dust — 
Carbonic  Acid — Effects  of  Impure  Air — Nature's  Provision  for 
Purifying  tJie  Air —  Ventilation — Animal  Heat — Spontaneous  Com- 
bustion. 

1.  The  Object  of  Respiration. — In  one  set  of  capil- 
laries, or  hair-like  vessels,  the  blood  is  impoverished  for  the 
support  of  the  different  members  and  organs  of  the  body. 
In  another  capillary  system  the  blood  is  refreshed  and  again 
made  fit  to  sustain  life.    The  former  belongs  to  the  greater 
or  systemic  circulation  ;  the  latter  to  the  lesser  or  pulmo- 
nary, so  called  from  pulmo,  the  lungs,  in  which  organs  it 
is  situated.     The  blood,  as  sent  from  the  right  side  of  the 
heart  to  the  lungs,  is  venous,  dark,  impure,  and  of  a  nature 
unfit  to  circulate  again  through  the  tissues.     But,  when 
the  blood  returns  from  the  lungs  to  the  left  side  of  the 
heart,  it  has  become  arterial,  bright,  pure,  and  no  longer 
hurtful  to  the  tissues.     This  marvellous  purifying  change 
is  effected  by  means  of  the  very  familiar  act  of  respiration, 
or  breathing. 

2.  The  Lungs. — The  lungs  are  the  special  organs  of 
respiration.     There  are  two  of  them,  one  on  each  side  of 
the  chest,  which  cavity  they,  with  the  heart,  almost  wholly 
occupy.     The  lung-substance  is  soft,  elastic,  and  sponge- 
like.   Under  pressure  of  the  finger,  it  crepitates,  or  crackles, 
and  floats  when  thrown  into  water  ;  these  properties  being 

1 .  Difference  between  the  two  sets  of  capillaries  ?    Change  effected  by  respira- 
tion or  breathing? 

2.  What  are  the  lungs?    How  many  lungs  are  there?    Lung-substance?    Its 
properties  ?    The  pleura  ? 


124 


RESPIRATION. 


due  to  the  presence  of  air  in  the  minute  air-cells  of  the 
lungs.  To  facilitate  the  movements  necessary  to  these 
organs,  each  of  them  is  provided  with  a  double  covering  of 
an  exceedingly  smooth  and  delicate  membrane,  called  the 


FIG.  34.— ORGANS  or  THE  CHEST. 


A,  Lungs. 

B,  Heart. 


D,  Pulmonary  Artery. 

E,  Trachea. 


pleura.  One  layer  of  the  pleura  is  attached  to  the  walls 
of  the  chest,  and  the  other  to  the  lungs;  and  they  glide, 
one  upon  the  other,  with  utmost  freedom.  Like  the  mem- 
brane which  envelops  the  heart,  the  pleura  secretes  its  own 
lubricating  fluid,  in  quantities  sufficient  to  keep  it  alwaye 
moist. 

3.  The  Air-Passages. — The  lungs  communicate  with 
the  external  air  by  means  of  certain  air-tubes,  the  longest  of 


3.  Communication  of  the  lungs  with  the  external  air  ?    Bronchial  tubes  ? 


RESPIRATION. 


which,  the  trachea,  or  windpipe,  runs  along  the  front  of  tl 
neck  (Fig.  34,  E,  and  35)  .With- 
in the  chest  this  tube  divides 
into  two  branches, one  entering 
each  lung;  these  in  turn  give 
rise  to  numerous  branches,  or 
bronchial  tubes,  as  they  are 
called,  which  gradually  dimin- 
ish in  size  until  they  are  about 
one- twenty-fifth  of  an  inch  in 
diameter.  Each  of  these  ter- 
minates in  a  cluster  of  little 
pouches,  or  "air-cells,"  having 
very  thin  walls,  and  covered 
with  a  capillary  network,  the 
most  intricate  in  the  body 
(Fig.  36). 

4.  These  tubes  are  some- 
what flexible,  sufficiently  so  to 
bend  when  the  parts  move  in 
which  they  are  situated ;  but 
they  are  greatly  strengthened 
by  bands  or  rings  of  cartilage 
which  keep  the  passages  always 
open;  otherwise  there  would 
be  a  constantly-recurring  ten- 
dency to  collapse  after  every 
breath.  The  lung-substance 
essentially  consists  of  these 
bronchial  tubes  and  terminal 
air-cells,  with  the  blood-ves- 
sels ramifying  .  about  them 
(Fig.  37).  At  the  top  of  the 

v        .     ,!      ,  ,      „   FIG.  36.— DIAGRAM  AND  SECTION  OP 

trachea  is  the  larynx,  a  sort  of  THE  AIR-CELLS. 


PIG.  35.— LARYNX,  TBACHEA,  AND 
BRONCHIAL  TUBES. 


4.  Office  of  the  bronchial  tubes  ?    What  further  can  you  state  of  them  ? 


126  RESPIRATION. 


box  of  cartilage,  across  which  are  stretched  the  vocal  cords. 
Here  the  voice  is  produced  chiefly  by  the  passage  of  the 
respired  air  over  these  cords,  causing  them  to  vibrate. 


FIG.  37. — SECTION  OF  THE  LUNGS. 

5.  Over  the  opening  of  the  larynx  is  found  the  epiglottis, 
which  fits  like  the  lid  of  a  box  at  the  entrance  to  the 
lungs,  and  closes  during  the  act  of  swallowing,  so  that 
food  and  drink  shall  pass  backward  to  the  oesophagus,  or 
gullet  (Fig.  38).  Occasionally  it  does  not  close  in  time, 
and  some  substance  intrudes  within  the  larynx,  when  we  at 
once  discover,  by  a  choking  sensation,  that  "something  has 
gone  the  wrong  way,"  and,  by  coughing,  we  attempt  to  ex- 
pel the  unwelcome  intruder.  The  epiglottis  is  one  of  the 
many  safeguards  furnished  by  nature  for  our  security  and 

5.  The  epiglottis  ?    When  it  does  not  close  in  time,  what  is  the  consequence? 


RESPIRATION. 


12? 


comfort,  and  is  planned  and  put  in  place  long  before  these 
organs  are  brought  into  actual  use  in  breathing  and  in 
taking  food. 


FIG.  38.— SECTION  OP  MOUTH  AND  THROAT. 
A,  The  Tongue.       C,  Vocal  C9rd.       N,  Trachea. 


B,  The  Uvula. 


E,  Epiglottis. 
L,  Larynx. 


O,  (Esophagus. 


6.  The  air -passages  are  linea  tnrough  nearly  their 
whole  extent  with  mucous  membrane,  which  maintains 
these  parts  in  a  constantly  moist  condition.  This  meni- 
brane  has  a  peculiar  kind  of  cells  upon  its  outer  stir- 

6.  Lining  of  the  air-passages?    Ciliated  cells?    Their  uses?    The  three  dis- 
eases of  the  lungs  ? 


128  RESPIRATION. 


face.  If  examined  under  a  powerful  microscope,  we  may 
see,  even  for  a  considerable  time  after  their  removal  from 
the  body,  that  these  cells  have  minute  hair-like  processes 
in  motion,  which  wave  like  a  field  of  grain  under  the 
influence  of  a  breeze  (Fig.  39).  This  is  a  truly  beauti- 
ful sight;  and  since  it  is  found  that  these  little  cilia,  as 
they  are  called,  always  produce  currents  in  one  direction, 
from  within  outward,  it  is  probable  that  they  serve  a 

useful  purpose  in  catching  and 
carrying  away  from  the  lungs 
dust  and  other  small  particles 
drawn  in  with  the  breath  (Fig. 
39).  The  three  diseases  which 
more  commonly  affect  the  lungs, 
as  the  result  of  exposure,  are 
FIG.  39.-ciLiATEi>  CELLS.  pneumonia,  or  inflammation  of 
the  lungs,  implicating  principally 

the  air-cells;  bronchitis,  an  inflammation  of  the  large  bron- 
chial tubes;  and  pleurisy,  an  inflammation  of  the  investing 
membrane  of  the  lungs,  or  pleura.  Among  the  young,  an 
affection  of  the  trachea  takes  place,  known  as  croup. 

7.  The  Movements  of  Respiration.— The  act  of 
breathing  has  two  parts — (1),  inspiration,  or  drawing 
air  into  the  lungs,  and  (2),  expiration,  or  expelling  it 
from  the  lungs  again.  In  inspiration,  the  chest  extends 
in  its  length,  breadth,  and  height,  or  width.  We  can 
prove  that  this  is  the  case  as  regards  the  two  latter,  by 
observing  the  effect  of  a  deep  breath.  The  ribs  are  ele- 
vated by  means  of  numerous  muscles,  some  of  which  oc- 
cupy the  entire  spaces  between  those  bones.  But  the 
increase  in  length,  or  vertically,  is  not  so  apparent,  as  it  is 
caused  by  a  muscle  within  the  body  called  the  diaphragm, 
it  being  the  thin  partition  which  separates  the  chest  from 
the  abdomen,  rising  like  a  dome  within  the  chest.  (Fig.  16). 

7.  The  act  of  breathing  ?    Extension  of  the  chest  by  breathing  ? 


RESPIRATION. 


8.  With  every  inspiration,  the  diaphragm  contracts,  and 
in  so  doing,  approaches  more  nearly  a  plane,  or  horizontal, 
surface,   and   thus   enlarges    the    capacity   of   the   chest. 
Laughing,  sobbing,  hiccoughing,  and  sneezing  are  caused 
by  the  spasmodic  or  sudden  contraction  of  the  diaphragm. 
The  special  power  of  this  muscle  is  important  in  securing 
endurance,  or  "  long  wind,"  as  it  is  commonly  expressed; 
which  may  be  obtained  mainly  by  practice.    It  is  possessed 
in  a  marked  degree  by  the  mountaineer,  the  oarsman,  and 
the  trained  singer.     As  the  walls  of  the  chest  extend,  the 
lungs  expand,  and  the  air  rushes  in  to  fill  them.      This 
constitutes  an  inspiration.     The  habit  of  taking  frequent 
and   deep   inspirations,   in    the   erect  position,   with   the 
shoulders  thrown  back,  tends  greatly  to  increase  the  ca- 
pacity and  power  of  the  organs  of  respiration. 

9.  Expiration  is  a  less  powerful  act  than  inspiration. 
The  diaphragm  relaxes  its  contraction,  and  ascends  in  the 
form  of  a  dome;  the  ribs  descend  and  contract  the  chest; 
while  the  lungs  themselves,  being  elastic,  assist  to  drive 
out  the  air.     The  latter  passes  out  through  the  same  chan- 
nels by  which  it  entered.     At  the  end  of  each  expiration 
there  is  a  pause,  or  period  of  repose,  lasting  about  as  long 
as  the  period  of  action. 

10.  Frequency  of  Respiration. — It  is  usually  esti- 
mated that  we  breathe  once  during  every  four  beats  of  the 
heart,  or  about  eighteen  times  in  a  minute.     There  is,  of 
course,  a  close  relation  between  the  heart  and  lungs,  and 
whatever  modifies  the  pulse,  in  like  manner  affects  the 
breathing.     When  the  action  of  the  heart  is  hurried,  a 
larger  amount  of  blood  is  sent  to  the  lungs,  and,  as  the 
consequence,  they  must  act  more  rapidly.     Occasionally, 
the  heart  beats  so  very  forcibly  that  the  lungs  cannot  keep 
pace  with  it,  and  then  we  experience  a  peculiar  sense  of 

8.  Contraction  of  the  diaphragm  ?    Power  of  the  diaphragm?    Effects  of  ex- 
tending the  wails  of  the  chest  ?  The  habit  of  taking  frequent  and  deep  inspirations '( 

9.  Expiration  ?    The  mechanism  of  expiration  ? 

1O.  Frequency  of  respiration  ?    Effect  of  hurried  action  of  the  heart? 

6* 


130  RESPIRATION. 


distress  from  the  want  of  air.  This  takes  place  when  we 
run  until  we  are  "  out  of  breath.7'  At  the  end  of  every 
fifth  or  sixth  breath,  the  inspiration  is  generally  longer 
than  usual,  the  effect  being  to  change  more  completely  the 
air  of  the  lungs. 

11.  Although,  as  a  general  rule,  the  work  of  respiration 
goes  on  unconsciously  and  without  exertion  on  our  part, 
it  is  nevertheless  under  the  control  of  the  will.     We  can 
increase  or  diminish  the  frequency  of  its  acts  at  pleasure, 
and  we  can  "hold  the   breath,"  or   arrest   it   altogether 
for  a   short   time.      From    twenty   to    thirty   seconds   is 
ordinarily  the  longest  period  in  which  the  breath  can  be 
held ;  but  if  we  first  expel  all  the  impure  air  from  the 
lungs,  by  taking  several  very  deep  inspirations,  the  time 
may  be  extended  to  one  and  a  half  or  even  two  minutes. 
This  should  be  remembered,  and  acted  upon,  before  pass- 
ing through  a  burning  building,  or  any  place  where  the 
air  is  very  foul.     The  arrest  of  the  respiration  may  be  still 
further  prolonged  by  training  and  habit ;  thus  it  is  said, 
the  pearl-fishers  of  India  can  remain  three  or  four  minutes 
under  water  without  being  compelled  to  breathe. 

12.  Capacity  of   the   Lungs. — The  lungs  are  not 
filled  and  emptied  by  each  respiration.     For  while  their 
full  capacity,  in  the  adult,  is  three  hundred  and   twenty 
cubic  inches,  or  more  than  a  gallon,  the  ordinary  breath- 
ing air  is  only  one-sixteenth  part  of  that  volume,  or  twenty 
cubic  inches,  being  two-thirds  of  a  pint.     Accordingly,  a 
complete  renovation,  or  rotation,  of  the  air  of  the  lungs 
does  not  take  place  more  frequently  than  about  once  in  a 
minute ;  and  by  the  gradual  introduction  of  the  external 
air,   its    temperature    is   considerably  elevated    before   it 
reaches  the  delicate  pulmonary  capillaries.      In  tranquil 
respiration,  less  than  two-thirds  of  the  breathing  power  is 


1 1 .  Respiration  controlled  by  the  will  ?    Advantage  of  the  knowledge  to  us  ? 

12.  Capacity  of  the  lungs  ?    Time  required  to  renovate  the  air  in  the  lungs  ? 
In  tranquil  respiration  ?  Importance  of  the  provision  ? 


RESPIRATION.  131 


called  into  exercise,  leaving  a  reserve  capacity  of  about  one 
hundred  and  twenty  cubic  inches,  equivalent  to  three  and 
one  half  pints.  This  provision  is  indispensable  to  the  con- 
tinuation of  life;  otherwise,  a  slight  embarrassment  of  res- 
piration, by  an  ordinary  cold,  for  instance,  would  suffice 
to  cut  off  the  necessary  air,  and  the  spark  of  life  would 
be  speedily  extinguished. 

13.  The  Air  we   breathe.— The  eartfi  is  enveloped 
on  all  sides  by  an  invisible  fluid,  called  the  atmosphere. 
It  forms  a  vast  and  shoreless  ocean  of  air,  forty-five  miles 
deep,  encircling  an4  pervading  all  objects  on  the  earth's 
surface,  which  is  absolutely  essential  for  the  preservation  of 
all  vegetable  and  animal  life, — in  the  sea,  as  well  as  on  the 
land  and  in  the  air.     At  the  bottom,  or  in  the  lower  strata 
of  this  aerial  ocean,  we  move  and  have  our  being.     Per- 
fectly pure  water  will  not  support  marine  life,  for  a  fish 
may  be  drowned  in  water  from  which  the  air  has  been  ex- 
hausted, just  as  certainly  as  a  mouse,  or  any  other  land 
animal,  will  perish  if  put  deeply  into  the  water  for  a  length 
of  time.     The  cause  is  the  same  in  both  cases :  the  animal 
is  deprived  of  the  requisite  amount  of  air.    It  is  also  stated, 
that  if  the  water-supply  of  the  plant  be  deprived  of  air,  its 
vital  processes  are  at  once  checked. 

14.  The  air  is  not  a  simple  element,  as  the  ancients  sup- 
posed, but  is  formed  by  the  mingling  of  two  gases,  known 
to  the  chemist  as  oxygen  and  nitrogen,  in  the  proportion 
of  one  part  of  the  former  to  four  parts  of  the  latter.    These 
gases  are  very  unlike,  being  almost  opposite  in  their  prop- 
erties: nitrogen  is  weak,  inert,  and  cannot  support  life; 
while  oxygen  is  powerful,  and  incessantly  active ;  and  is  the 
essential  element  which  gives  to  the  atmosphere  its  power 
to  support  life  and  combustion.     The  discovery  of  this  fact 
was  made  bv  the  French  chemist,  Lavoisier,  in  1778. 


13.  The  atmosphere  ?    How  high  or  deep  ?    How  essential  to  life  ?    Marine  lift 
in  perfectly  pure  water  and  air  ? 

14.  Composition  of  the  air  ?    Properties  of  the  two  gases  ? 


132  RESPIRATION. 

15.  Changes  in  the  Air  from  Respiration. — Air 

that  has  been  once  breathed  is  no  longer  fit  for  respiration. 
An  animal  confined  within  it  will  sooner  or  later  die;  so 
too,  a  lighted  candle  placed  in  it  will  be  at  once  extin- 
guished. If  we  collect  a  quantity  of  expired  air  and  ana- 
lyze it,  we  shall  find  that  its  composition  is  not  the  same 
as  that  of  the  inspired  air.  When  the  air  entered  the 
lungs  it  was  rich  in  oxygen ;  now  it  contains  twenty-five 
per  cent,  less  of  that  gas.  Its.  volume,  however,  remains 
nearly  the  same ;  its  loss  being  replaced  by  another  and 
very  different  gas,  which  the  lungs  exhaled,  called  carbonic 
acid,  or,  as  the  chemist  terms  it,  carbon  dioxide. 

16.  The  expired  air  has  also  gained  moisture.     This  is 
noticed  when  we  breathe  upon  a  mirror,  or  the  window- 
pane,  the  surface  being  tarnished  by  the  condensation  of 
the  watery  vapor  exhaled  by  the  lungs.     In  cold  weather, 
this  causes  the  fine  cloud  which  is  seen  issuing  from  the 
nostrils  or  mouth  with  each  expiration,  and  contributes  in 
forming  the  feathery  crystals  of  ice  which  decorate  our 
window-panes  on  a  winter's  morning. 

17-  This  watery  vapor  contains  a  variable  quantity  of 
animal  matter,  the  exact  nature  of  which  is  unknown;  but 
when  collected  it  speedily  putrefies  and  becomes  highly 
offensive.  From  the  effects,  upon  small  animals,  of  con- 
finement in  their  own  exhalations,  having  at  the  same 
time  an  abundant  supply  of  fresh  air,  it  is  believed  that 
the  organic  matters  thrown  off  by  the  lungs  and  skin 
are  direct  and  active  poisons;  and  that  to  such  emana- 
tions from  the  body,  more  than  to  any  other  cause,  are 
due  the  depressing  and  even  fatal  results  which  follow  the 
crowding  of  large  numbers  of  persons  into  places  of  lim- 
ited capacity. 

1  !i.  Air  once  breathed  ?    An  animal  in  it  ?    A  candle  ?    Analysis  of  expired  air  ? 
Change  in  volume  ? 

1 6.  What  else  has  the  expired  air  pained  ?    When  and  where  noticed  ? 

17.  Nature  of  the  watery  vapor  ?    Its  effects  upon  animals  ? 


R-ESPIRATIOtf.  133 


18.  History  furnishes  many  painful  instances  of  the  ill 
effects  of  overcrowding.     In   1756,  of  one   hundred  and 
forty-six   Englishmen   imprisoned  in  the  Black   Hole  of 
Calcutta,   only  twenty-three,  at  the   end  of  eight  hours, 
survived.     After  the  battle   of  Austerlitz,  three  hundred 
prisoners  were  crowded  into   a   cavern,  where,  in  a  few 
hours,   two-thirds   of  their  number   died.      On   board  a 
steam-ship,   during   a   stormy    night,    one   hundred   and 
fifty  passengers    were    confined    in   a   small    cabin,    but 
when  morning  came,  only  eighty  remained  alive. 

19.  Changes  in  the  Blood  from  Respiration.— 
The  most  striking  change  which  the  blood  undergoes  by 
its  passage  through  the  lungs,  is  the  change  of  color  from 
a  dark  blue  to  bright  red.     That  this  change  is  dependent 
upon   respiration   has  been   fully  proved   by  experiment. 
If  the  trachea,  or  windpipe,  of  a  living  animal  be  so  com- 
pressed as  to  exclude  the  air  from,  the  lungs,  the  blood  in 
the  arteries  will  gradually  "grow  darker,  until  its  color  is 
thelrame  as  that  of  the  venous  blood.     When  the  pressure 
is  removed   the^  blood   speedily   resumes    its   bright  hue. 
Again,  if  the  animal  be  made  to.  breathe  an  atmosphere 
containing  more  oxygen  than  atmospheric  air,  the  color 
changes    from   scarlet    to   vermilion,   and    becomes   even 
brighter  than  arterial  blood.     This  change  of  color  is  not 
of  itself  a  very  important  matter,  but  it  indicates  a  most 
important  change  of  composition. 

20.  The  air,  as  we  have  seen,  by  respiration  loses  oxy- 
gen and  gains  carbonic  acid :  the  blood,  on  the  contrary, 
gains  oxygen  and  loses  carbonic  acid.     The  oxygen  is  the 
food  of  the  blood  corpuscles;  while  the  articles  we  eat  and 
drink  belong  more  particularly  to  the  plasma  of  the  blood. 
The  air,  then,  it  is  plain,  is  a  sort  of  food,  and  we  should 

18.  Give  some  of  the  instances  furnished  by  history. 

If).  Change  in  the  blood  from  blue  to  red.  Upon  what  does  the  change  depend  ? 
How  shown  ? 

2O.  What  does  the  air  lose  and  gain  by  respiration  ?  What,  the  blood  ?  Air  as 
food? 


134  RESPIRATION. 


undoubtedly  so  regard  it,  if  it  were  not  for  the  fact  that 
we  require  it  constantly,  instead  of  taking  it  at  stated  in- 
tervals, as  is  the  case  with  our  articles  of  diet.  Again,  as 
the  demand  of  the  system  for  food  is  expressed  by  the  sen- 
sation of  hunger,  so  the  demand  for  air  is  marked  by  a 
painful  sensation  called  suffocation. 

21.  Interchange  of  Gases  in  the  Lungs. — As  the 
air  and  the  blood  are  not  in  contact,  they  being  separated 
from  each  other  by  the  walls  of  the  air-cells  and  of  the 
blood-vessels,  how  can  the  two  gases,  oxygen  and  carbonic 
acid,  exchange  places  ?     Moist  animal  membranes  have  a 
property  which  enables  them  to  transmit  gases  through 
their  substance,  although  they  are  impervious  to  liquids. 
This  may  be  beautifully  shown  by  suspending  a  bladder 
containing  dark  blood  in  a  jar  of  oxygen.     At  the  end  of 
a  few  hours  the  oxygen  will  have  disappeared,  the  blood 
will  be  brighter  in  color,  and  carbonic  acid  will  be  found 
in  the  jar. 

22.  If  this  interchange  takes  place  outside  of  the  body, 
how  much  more  perfectly  must  it  take  place  within,  where 
it  is   favored   by  many   additional   circumstances!     The 
walls  of  the  vessels  and  the  air-cells  offer  no  obstacle  to 
this  process,  which  is  known  as  gaseous  diffusion.     Both 
parts  of  the  process  are  alike  of  vital  importance.     If  oxy- 
gen be  not  received,  the  organs  cease  to  act;  and  if  car- 
bonic acid  be  retained  in  the  blood,  its  action  is  that  of  a 
poison ;   unconsciousness,  convulsions,  and  death  follow- 
ing. 

23.  Difference  between  Arterial  and  Venous 
Blood. — The  following  table  presents  the  essential  points 
of  difference   in   the  appearance  and  composition  of  the 
blood,  before  and  after  its  passage  through  the  lungs : — 


21 .  Moist  animal  membranes  ?    How  shown  with  the  bladder  ? 

22.  Gaseous  diffusion?    If  oxygen  be  not  received?    If  carbonic  acid  be  re- 
tained? 

23.  Difference  in  the  appearance  and  composition  of  the  blood?    Temperature 
of  the  hlood  ?    The  blood  while  passing  through  the  lungs  ?    The  consequence  ? 


RESPIRATION.  135 


Venous  Blood. 

Arterial  Blood. 

Color, 

Dark  blue, 

Scarlet. 

Oxygen, 

8  per  cent, 

18  per  cent. 

Carbonic  Acid, 

15  to  20  per  cent., 

6  per  cent.,  or  less. 

Water, 

More, 

Less. 

The  temperature  of  the  blood  varies  considerably;  but 
the  arterial  stream  is  generally  warmer  than  the  venous. 
The  blood  imparts  heat  to  the  air  while  passing  through 
the  lungs,  and  consequently  the  contents  of  the  right  side 
of  the  heart  has  a  higher  temperature  than  the  contents 
on  the  left  side. 

24.  By   means   of  the  spectroscope,  we   learn  that   the 
change  of  color  in  the  blood  has  its  seat  in  the  corpuscles ; 
and  that,  according  as  they  retain  oxygen,  or  release  it,  they 
present  the  spectrum  of  arterial  or  venous  blood.     There 
evidently  exists,  on  the  part  of  these  little  bodies,  an  affin- 
ity for  this  gas,  and  hence  they  have  been  called  "  carriers 
of  oxygen."     It  was  long  ago  thought  that  blue  blood  was 
a  trait  peculiar  to  persons  of  princely  and  royal  descent, 
and  boastful  allusions  to  the  "  sang  azure"  of  kings  and 
nobles  are  quite  often  met  with.     Physiology,  however,  in- 
forms us  that  blue  blood  flows  in  the  veins  of  the  low  as 
well  as  the  high,  and  that  so  far  from  its  presence  indicat- 
ing a  mark  of  purity,  it,  in  reality,  represents  the  waste  and 
decay  of  the  system. 

25.  Amount  of  Respiratory  Labor.  —  During  or- 
dinary calm  respiration,  we  breathe  eighteen  times  in  a 
minute;  and  twenty  cubic  inches  of  air  pass  in  and  out  of 
the  lungs  with  every  breath.     This  is  equivalent  to  the  use 
of  three  hundred  and  sixty  cubic  inches,  or  more  than  ten 
pints  of  air  each  minute.     From  this  we  calculate  that  the 
quantity  of  air  which  hourly  traverses  the  lungs  is  about 
thirteen  cubic  feet,  or  seventy-eight  gallons;  and  daily,  not 


24.  What  do  we  learn  by  means  of  the  spectroscope  ?     "  Carriers  of  oxygen  ?" 
Blue  blood  in  the  system  ? 

25.  The  amount  of  air  that  passes  in  and  out  of  the  lungs  ? 


136  RESPIRATION. 


less  than  three  hundred  cubic  feet,  an  amount  nearly  equal ' 
to  the  contents  of  sixty  barrels. 

26.  Of  this  large  volume  of  air  five  per  cent,  is  absorbed 
in  its  transit  through  the  lungs.     The  loss  thus  sustained  is 
almost  wholly  of  oxygen,  and  amounts  to  fifteen  cubic  feet 
daily.     The  quantity  of  carbonic  acid  exhaled  by  the  lungs 
during  the  day  is  somewhat  less,  being  twelve  cubic  feet. 
Under  the  influence  of  excitement  or  exertion,  the  breath- 
ing becomes  more  frequent  and  more  profound ;  and  then 
the   internal   respiratory  work   increases   proportionately, 
and  may  even  be  double  that  of  the  above  estimate.     It 
has  been  estimated  that  in  drawing  a  full  breath,  a  man 
exerts  a  muscular  force   equal   to   raising  two   hundred 
pounds  placed  upon  the  chest. 

27.  Impurities  of  the  Air. — The  oxygen  in  the  at- 
mosphere is  of  such  prime  importance,  and  its  proportion 
is  so  nicely  adjusted  to  the  wants  of  man,  that  any  gas  or 
volatile  substance  which  supplants  it  must  be  regarded  as 
a  hurtful  impurity.     All  gases,  however,  are  not  alike  in- 
jurious.    Some,  if  inhaled,  are   necessarily  fatal ;   arsen- 
uretted  hydrogen  being  one  of  these,  a  single  bubble  of 
which  destroyed  the  life  of  its  discoverer,  Gehlen.     Others 
are  not  directly  dangerous,  but  by  taking  the   place  of 
oxygen,  and  excluding  it  from  the  lungs,  they  become  so. 
Into  this  latter  class  we  place  carbonic  acid. 

28.  Most  of  the  actively  poisonous  gases  have  a  pungent 
or  offensive  odor;  and,  as  may  be  inferred,  most  repugnant 
odors  indicate  the  presence  of  substances  unfit  for  respira- 
tion.   Accordingly,  as  we  cannot  see  or  taste  these  impu- 
rities, the  sense  of  smell  is  our  principal  safeguard  against 
them ;  and  we  recognize  the  design  which  has  planted  this 
sense,  like  a  sentinel  at  the  proper  entrance  of  the  air- 


26.  Air  absorbed  in  its  transit  through  the  lungs  ?    The  loss  ?    Carbonic  acid 
exhaled  ?    Effect  of  excitement  or  exertion  ?    What  estimate  ? 

27.  Importance  of  the  oxygen  in  the  atmosphere?    Injurious  character  of 


28.  Pungency  of  gases  ?    The  inference  ?    Our  safeguard  ? 


RESPIRATION.  137 


passages,  the  nostrils,  to  give  as  warning  of  approaching 
harm.  Take,  as  an  example,  the  ordinary  illuminating 
gas  of  cities,  from  which  so  many  accidents  happen.  How 
many  more  deaths  would  it  cause  if,  when  a  leak  occurs, 
we  were  not  able  to  discover  the  escape  of  the  gas  by  means 
of  its  disagreeable  odor. 

29.  Organic  matters  exist  in  increased  measure  in  the 
expired  breath  of  sick  persons,  and  impart  to  it,  at  times,  a 
putrid  odor.     This  is  especially  true  in  diseases  which, 
like   typhus  and   scarlet   fever,  are  •  referable  to  a  blood 
poison.     In  such  cases  the  breath  is  one  of  the  -means  by 
which  nature  seeks  to  expel  the  offending  material  from 
the  system.     Hence,  those  who  visit  or  administer  to  fever- 
sick  persons  should  obey  the  oft-repeated  direction,  "  not 
to  take  the  breath  of  the  sick."     At  such  times,  if  ever, 
fresh  air  is  demanded,  not  alone  for  the  sick,  but  as  well 
for  those  who  are  in  attendance. 

30.  Dust  in  the  Air. — Attention  has  lately  been  di- 
rected to  the  dust,  or  haze,  that  marks  the  ray  of  sunshine 
across  a  shaded  room.    Just  as,  many  years  ago,  it  was  dis- 
covered that  myriads  of  animalcula  infested  much  of  the 
water  we  drank,  so  now  the  microscope  reveals  "the  gay 
motes  that  dance  along  a  sunbeam"  to  be,  in  part,  com- 
posed of  multitudes  of  animal  and  vegetable  forms  of  a 
very  low  grade,  the  germs  of  fermentation  and  putrefac- 
tion, and  the  probable  sources  of  disease. 

31.  It  is  found  that  the  best  filter  by  which  to  separate 
this  floating  dust  from  the  air  is  cotton  wool,  although  a 
handkerchief  will  imperfectly  answer  the   same   purpose. 
In  a  lecture  on  this  subject  by  Prof.  Tyndall,  he  remarks 
that,  "  by  breathing  through  a  cotton  wool  respirator,  the 
noxious  air  of  the  sick  room  is  restored  to  practical  purity. 
Thus  filtered,  attendants  may  breathe  the  air  unharmed. 


29.  The  air  of  rooms  in  which  fever-sick  persons  are  confined  ? 

30.  Animalcula  in  the  water?     Dust  in  the  air  ? 

3 1 .  The  best,  air  filter  ?    The  remarks  of  Prof.  Tyndall  ? 


138  RESPIRATION. 


In  all  probability,  the  protection  of  the  lungs  will  be  the 
protection  of  the  whole  system.  For  it  is  exceedingly 
probable  that  the  germs  which  lodge  in  the  air-passages 
are  those  which  sow  epidemic  disease  in  the  body.  If  this 
be  so,  then  disease  can  certainly  be  warded  oif  by  niters  of 
cotton  wool.  By  this  means,  so  far  as  the  germs  are  con- 
cerned, the  air  of  the  highest  Alps  may  be  brought  into 
the  chamber  of  the  invalid." 

32.  Carbonic  Acid  in   the  Air. — We  have  already 
spoken  of  this  gas  as -an  exhalation  from  the  lungs,  and  a 
source  of  impurity;  but  it  exists  naturally  in  the  atmos- 
phere in  the  proportion  of  one  half  part  per  thousand.     In 
volcanic  regions  it  is  poured  forth  in  enormous  quantities 
from  fissures  in  the  earth's  surface.     Being  heavier  than 
air,  it  sometimes  settles  into  caves  and  depressions  in  the 
surface.     It  is  stated  that  in  the  island  of  Java,  there  is  a 
place  called  the  "  Valley  of  Poison,"  where  the  ground  is 
covered  with  the  bones  of  birds,  tigers,  and  other  wild  ani- 
mals, which  were  suffocated  by  carbonic  acid  while  passing. 
The  Lake  Avernus,  the  fabled  entrance  to  the  infernal  re- 
gions, was,  as  its  name  implies,  bird-less,  because  the  birds, 
while  flying  over  it,  were  poisoned  by  the  gas  and  fell  dead 
into  its  waters.    In  mines,  carbonic  acid  forms  the  dreaded 
choke-dam}),  while  carburetted  hydrogen  is  the  fire-damp. 

33.  In  the  open  air,  men  seldom  suffer  from  carbonic 
acid,  for,  as  we  shall  see  presently,  nature  provides  for  its 
rapid   distribution,  and   even   turns  it  to  profitable  use. 
But  its  ill  effects  are  painfully  evident  in  the  abodes  of 
men,  in  which  it  is  liable  to  collect  as  the  waste  product  of 
respiration  and  of  that  combustion  which  is  necessary  for 
lighting  and  warming  our  homes.     A  man  exhales,  during 
repose,  not  less  than  one-half  cubic  foot  of  carbonic  acid 
per  hour.     One  gas-burner  liberates  five  cubic  feet  in  the 


32.  Carbonic  acid  in  volcanic  regions ?  In  Java?  At  Lake  Avernus  ?  In  mines? 

33.  In  the  open  air?    Amount  of  carbonic  acid  exhaled  by  a  man?    A  gas- 
burner  ?    A  room  fire  ?     From  furnaces  ? 


RESPIRATION.  139 


same  time,  and  spoils  about  as  much  air  as  ten  men.  A 
fire  burning  in  a  grate  or  stove  emits  some  gaseous  impur- 
ity, and  at  the  same  time  abstracts  from  the  air  as  much 
oxygen  as  twelve  men  would  consume  in  the  same  period, 
thus  increasing  the  relative  amount  of  carbonic  acid  in 
the  air.  From  furnaces,  as  ordinarily  constructed,  this  gas, 
with  other  products  of  combustion,  is  constantly  leaking 
and  vitiating  the  air  of  tightly-closed  apartments. 

34.  Effects  of  Impure  Air. — Carbonic  acid,  in  its 
pure  form,  is  irrespirable,  causing  rapid  death  by  suffoca- 
tion.    Air  containing  forty  parts  per  thousand  of  this  gas 
(the  composition  of  the  expired  breath)  extinguishes  a 
lighted  candle,  and  is  fatal  to  birds ;  when  containing  one 
hundred  parts,  it  no   longer  yields  oxygen  to   man   and 
other  warm-blooded  animals;   and  is  of  course   at  once 
fatal  to  them.     In  smaller  quantities,  this  gas  causes  head- 
ache, labored  respiration,  palpitation,  unconsciousness,  and 
convulsions.  , 

35.  In  crowded  and  badly  ventilated  apartments,  where 
the  atmosphere  relatively  contains  from  six  to  ten  times 
the  natural  amount  of  carbonic  acid,  the  contaminated  air 
causes  dulness,  drowsiness,  and  faintness;  the  dark,  im- 
pure blood  circulating  through  the  brain,  oppressing  that 
organ  and  causing  it  to  act  like  a  blunted  tool.     This  is  a 
condition  not  uncommon  in  our  schools,  churches,  court- 
rooms, and  the  like,  the  places  of  all  others  where  it  is 
desirable  that  the  mind  should  be  alert  and  free  to  act; 
but,  unhappily,  an  unseen  physiological  cause  is  at  work, 
dispensing  weariness  and  stupor  over  juries,  audience,  and 
pupils. 

36.  Another  unmistakable  result  of  living  in  and  breath- 
ing foul  air  is   found  in   certain   diseases  of  the  lungs, 
especially  consumption.     For  many  years  the  barracks  of 


34.  Effects  of  inhaling  carbonic  acid  alone  ?    In  email  quantities? 

35.  Effects  of  the  air  in  crowded  and  badly  ventilated  rooms? 

36.  A  cause  of  consumption  ?    How  was  the  fact  illustrated  ? 


140  RESPIRATION. 


the  British  army  were  constructed  without  any  regard  to 
ventilation;  and  during  those  years  the  statistics  showed 
that  consumption  was  the  cause  of  a  very  large  proportion 
of  deaths.  At  last  the  government  began  to  improve  the 
condition  of  the  buildings,  giving  larger  space  and  air- 
supply;  and  as  a  consequence,  the  mortality  from  con- 
sumption has  diminished  more  than  one-third. 

37.  The  lower  animals  confined  in  the  impure  atmos- 
phere of  menageries,  contract  the  same  diseases  as  man. 
Those  brought  from  a  tropical  climate,  and  requiring  arti- 
ficial warmth,  generally  die  of  consumption.     In  the  Zoo- 
logical  gardens   of  Paris,  this  disease  affected  nearly  all 
monkeys,  until  care  was  taken  to  introduce  fresh  air  by 
ventilation;  and  then  it  almost  wholly  disappeared.     The 
tendency  of  certain   occupations  to   shorten  life   is  well 
known;  disease  being  occasioned  by  the  fumes  and  dust 
which  arise  from  the  material  employed,  in  addition  to  the 
unhealthful  condition  of  the  workshop  or  factory  where 
many  hours  are  passed  daily. 

38.  The  following  table  shows  the  comparative  amount 
of  carbonic  acid  in  the  air  under  different  conditions  and 
the  effects  sometimes  produced: — 

PROPORTION  OP  CARBONIC  ACID.  in  1000  parts  of  Air. 

Air  of  country .4 

"     "city 5 

In  hospital,  well  ventilated 6 

In  school,  church,  etc.,  fairly  ventilated 1.2  to  2.5 

In  court-house,  factory,  etc.,  without  ventilation. ...       4.    to  40. 

In  bedroom,  before  being  aired 4.5 

In  bedroom,  after  being  aired 1.5 

Constantly  breathed,  causing  ill  health 2. 

Occasionally  breathed,  causing  discomfort 3. 

Occasionally  breathed,  causing  distress 10. 

Expired  air 40. 

Air  no  longer  yielding  oxygen  100. 

37.  How,  in  the  case  of  the  lower  animals*  ?    Tendency  of  certain  occupations  ? 

38.  Give  the  fact  as  set  forth  in  the  table. 


RESPIRATION.  141 


39.  Nature's  Provision  for  Purifying  the  Air. — 

We  have  seen  that  carbonic  acid  is  heavier  than  air,  and 
is  poisonous.  Why,  then,  does  it  not  sink  upon  and  over- 
whelm mankind  with  a  silent,  invisible  wave  of  death  ? 
Among  the  gases  there  is  a  more  potent  force  than  gravity, 
which  forever  precludes  such  a  tragedy.  It  is  known  as 
the  diffusive  power  of  gases.  It  acts  according  to  a  defi- 
nite law,  and  with  a  resistless  energy  compelling  these 
gases,  when  in  contact,  to  mingle  until  they  are  thor- 
oughly diffused.  The  added  influence  of  the  winds  is 
useful,  by  insuring  more  rapid  changes  in  the  air;  air  in 
motion  being  perfectly  wholesome.  The  rains  also  wash 
the  air. 

40.  We  have  seen  that  the  whole  animal  creation  is  con- 
stantly abstracting  oxygen  from  the  atmosphere,  and  as 
constantly  adding  to  it  vast  volumes  of  a  gas  injurious  alike 
to  all,  even  in  small  quantities.     How,  then,  does  the  air  re- 
tain, unchanged,  its  life-giving  properties  ?     The  constant 
purity  of  the  air  is  secured  by  means  of  the  vegetable  cre- 
ation.    Carbonic  acid  is  the  food  of  the  plants,  and  oxygen 
is  its  waste  product.     The  leaves  are  its  lungs,  and  under 
the  stimulus  of  sunlight  a  vegetable  respiration  is  set  in 
motion,  the  effects  of  which  are  just  the  reverse  of  the 
function  we  have  been  considering.     Thus  nature  purifies 
the  air,  and  at  the  same  time  builds  up  beautiful  and  use- 
ful forms  of  life  from  elements  of  decay. 

41.  In  the  sea,  as  in  the  air,  the  same  circle  of  changes 
is  observed.     Marine  animals  consume  oxygen  and  give  off 
carbonic  acid;  while  marine  plants  consume  carbonic  acid 
and  liberate  oxygen.     Taking  advantage  of  this  fact,  we 
may  so  arrange  aquaria  with  fishes  and  sea-plants,  in  their 
proper  combinations,  so  that  each  supplies  the  needs  of  the 
other,  and  the  water  requires  seldom  to  be  renewed.     This 

39.  What  can  you  state  of  the  diffusive  power  of  gases  ?    The  added  influence 
of  the  winds  ? 

40.  How  is  the  constant  purity  of  the  air  secured  ?    Explain  the  process  ? 

41.  What  process  occurs  in  the  sea  J    How  is  the  fact  illustrated  ? 


142  RESPIRATION. 


affords  us,  on  a  small  scale,  an  illustration  of  the  mutual 
dependence  of  the  two  great  kingdoms  of  nature;  as  well 
as  of  those  compensating  changes  which  are  taking  place 
on  such  a  grand  scale  in  the  world  about  us. 

42.  Ventilation. — Since  the  external  atmosphere,  as 
provided  by  nature,  is  always  pure,  and  since  the  air  in  our 
dwellings  and  other  buildings  is  almost  always  impure,  it 
becomes  imperative  that  there  should  be  a  free  communica- 
tion from  the  one  to  the  other.    This  we  aim  to  accomplish 
by  ventilation.     As  our  houses  are  ordinarily  constructed, 
the  theory  of  ventilation,  "to  make  the  internal  as  pure  as 
the  external  air,"  is  seldom  carried  out.     Doors,  windows, 
and  flues,  the  natural  means  of  replenishing  the  air,  are 
too  often  closed,  almost  hermetically,  against  the  precious 
element.     Special  means,  or  special  attention,  must  there- 
fore be  used  to  secure  even  a  fair  supply  of  fresh  air.     This 
is  still  more  true  of  those  places  of  public  resort,  where 
many  persons  are  crowded  together. 

43.  If  there  are  two  openings  in  a  room,  one  as  a  vent 
for  foul  air,  and  the  other  an  inlet  for  atmospheric  air, 
and  if  the  openings  be  large,  in  proportion  to  the  number 
of  air  consumers,  the   principal  object  will  be  attained. 
Thus,  a  door  and  window,  each  opening  into  the  outer  air, 
will  ordinarily  ventilate  a  small  apartment;  or  a  window 
alone  will  answer,  if  it  be  open  both  above  and  below,  and 
the  open  space  at  each  end  be  not  less  than  one  inch  for 
each  occupant  of  the  room,  when  the  window  is  about  a 
yard  wide.     The  direction  of  the  current  is  generally  from 
below  upward,  since   the   foul,  heated  air   tends  to  rise; 
but  this  is  not  essential.     Its  rate  need  not  be  rapid  ;  a 
"  draught,"  or  perceptible  current,  is  never  necessary  to 
good  ventilation.     The   temperature  of  the  air  admitted 
may  be  warm  or  cold.     It  is  thought  by  many  that  if  the 


42.  Character  of  the  external  air?  Of  the  air  in  our  dwellings  ?  What  becomes 
imperative  ?    Imperfect  ventilation  of  our  dwellings  ? 

43.  What  hints  are  given  for  the  ventilation  of  our  dwellings? 


RESPIRATION.  143 


air  is  cold,  it  is  pure ;  but  this  is  an  error,  since  cold  air 
will  receive  and  retain  the  same  impurities  as  warm  air. 

44.  Shall  we  open  our  bedrooms  to  the  night  air  ?    Flor- 
ence Nightingale  says,  in  effect,  that  night  air  is  the  only 
air  that  we  can  then  breathe.   "The  choice  is  between  pure 
air  without  and  impure  air  within.    Most  people  prefer  the 
latter, — an  unaccountable  choice.     An  open  window,  most 
nights  in  the  year,  can  hurt  no  one.     In  great  cities,  night 
air  is  the  best  and  purest  to  be  had  in  twenty-four  hours. 
I  could  better  understand,  in  towns,  shutting  the  windows 
during  the  day  than  during  the  night." 

45.  Animal  Heat. — Intimately  connected  with  respi- 
ration is  the  production  of  animal  heat,  or  the  power  of 
maintaining  the  temperature  of  the  body  above  that  of  the 
medium  in  which  the  creature  moves;  thus,  the  bird  is 
warmer  than  the  air,  and  the  fish  than  the  water.     This 
elevation  of  temperature  is  a  result  of  the  various  chemi- 
cal changes  which  are  constantly  taking  place  in  the  system. 
Although   common   to  all  animals,   in   a  greater  or  less 
degree,  heat  is  not  peculiar  to  them ;  since  plants  also  gen- 
erate it,  especially  at  the  time  of  sprouting  and  flowering. 
If  a  thermometer  be  placed  in  a  cluster  of  geranium  flow- 
ers, it  will  indicate  a  temperature  several  degrees  above 
that  of  the  surrounding  air. 

46.  Among  animals  great  differences  are  noticed  in  this 
respect,  but  the  degree  of  heat  produced  is  always  propor- 
tional to  the  activity  of  respiration  and  the  amount  of 
oxygen  consumed.     Accordingly,  the  birds,  whose  habits 
are  extremely  active,  and  whose  breathing  capacity  is  the 
greatest,  have  uniformly  the  highest  temperature.     Slug- 
gish animals,  on  the  contrary,  as  frogs,  lizards,  and  snakes, 
have  little  need  for  oxygen,  and   have  incompletely  de- 


44.  State  what  Florence  Nightingale  says  about  inhaling  night  air? 

45.  Warmth  of  the  bird  as  compared  with  that  of  the  air?    Of  the  fish  and 
the  water  ?    Heat  in  animals  and  plants  ?    How  illustrated  with  the  thermometer  ? 

46.  Amount  of  heat  in  animals,  how  apportioned?      As  regards  the  birds? 
Frogs,  and  other  sluggish  animals  ?    Arrangement  made  by  zooligsts  ? 


144  RESPIRATION. 


veloped  lungs ;  these  animals  are  cold  to  the  touch,  that  is, 
they  have  relatively  a  lower  temperature  than  man,  and 
their  positive  temperature  is  but  little  above  that  of  the 
external  air.  Accordingly,  zoologists  have  so  arranged  the 
animal  kingdom  that  warm-Hooded  animals,  including 
man,  the  Ijff  ds,  and  the  quadrupeds,  are  classified  together ; 
while  the  cold-blooded  animals,  such  as  the  fish,  tortoise, 
frog,  and  all  that  have  no  vertebral  column,  are  classed 
by  themselves. 

47.  The  temperature  of  the  human  body  is  about  100° 
Fahrenheit,  and  remains  about  the  same  through  winter 
and  summer,  in  the  tropics  as  well  as  in  the  frozen  regions 
of  the  north.     It  may  change  temporarily  within  the  range 
of  about  twelve  degrees;  but  any  considerable,  or  long-con- 
tinued elevation  or  diminution  of  the  bodily  heat  is  certain 
to  result  disastrously. 

48.  Man   is   able   to  adapt  himself  to  all  extremes  of 
climate;  and,  in  fact,  by  means  of  clothing,  shelter,  and 
food,  is  able  to  create  for  himself  an  artificial  climate  where- 
ever  he  choses  to  reside.     The  power  to  resist  cold  consists 
chiefly  in  preventing  the  heat  which  is  generated  by  the 
vital  processes  of  the  body  from  being  lost  by  radiation. 
Warm  clothing,  such  as  we  wear  in  winter,  has,  in  reality, 
the  same  temperature  as  that  which  is  worn  in  summer ; 
but,  by  reason  of  being  thick  and  porous,  it  is  a  bad  con- 
ductor  of   heat,   and   thus  prevents  the   escape   of  that 
produced  by  the  body.     If  woollen  fabrics  were  intrinsically 
warm,  no  one  would  wrap  a  piece  of  flannel,  or  blanket, 
around  a  block  of  ice  to  prevent  its  melting  in  summer. 

49.  The  faculty  of  generating  heat  explains  how  it  is 
that  we  are  enabled  to  resist  the  effects  of  cold;  but  how 
does  the  body  withstand  a  temperature   higher  than  its 


47.  State  what  is  said  respecting  the  temperature  of  the  human  body. 

48 1  Ability  of  man  to  adapt  himself  to  different  climates  ?  In  what  does  the 
power  to  resist  cold  consist  ?  What  is  said  about  warm  clothing  ? 

49»  Men  in  an  atmosphere  above  the  boiling-point  ?  In  foundries  and  glass 
works  ? 


RESPIRATION.  145 


own  ?  Men  have  been  known  to  remain  several  minutes  in 
an  atmosphere  heated  above  the  boiling-point  of  water,  and 
yet  the  temperature  of  their  own  bodies  was  not  greatly  ele- 
vated. Those  who  labor  in  foundries  and  glass-works  are 
habitually  subjected  to  very  high  degrees  of  temperature, 
but  they  do  not  suffer  in  health  more  than  thosie  engaged 
in  many  other  occupations. 

50.  The  regulation  of  the  temperature  of  the  body  is 
effected  by  means  of  perspiration,  and  by  its  evaporation. 
So  long  as  the  skin  acts  freely  and  the  air  freely  absorbs 
the  moisture,  the  heat  of  the  body  does  not  increase,  for 
whenever  evaporation  takes  place,  it  is  attended  by  the 
abstraction  of  heat — that  is,  the  part  becomes  relatively 
colder.     This  may  be  tested  by  moistening  some  part  of 
the  surface  with  cologne,  ether,  or  other  volatile  liquid, 
and  then  causing  it  to  evaporate  rapidly  by  fanning.     The 
principle   that   evaporation   produces   cold   has   been  in- 
geniously and  practically  employed,  in  the  manufacture 
of  ice,  by  means  of  freezing  machines. 

51.  Spontaneous  Combustion. — Is  it  possible  that 
the  temperature  of  the  living  body  can  be  so  increased, 
that  its  tissues  will  burn  spontaneously  ?     From  time  to 
time,  cases  have  been  reported  in  which,  by  some  mysteri- 
ous means,  considerable  portions  of  the  human  body  have 
been  consumed,  apparently  by  fire,  the  victim  being  found 
dead,  or  incapable  of  explaining  the  occurrence.     Hence, 
the  theory  has  been  current  that,  under  certain  condi- 
tions, the  tissues  of  the  body  might  become  self-ignited ; 
and  the  fact   that  this  so-called  spontaneous  combustion 
has  ordinarily  taken  place  in  those  who  had  been  addicted 
to  the  use  of  alcoholic  drinks,  has  given  a  color  of  proba- 
bility to  the  opinion.     It  has  been  supposed  that  the  flesh 
of  these  unfortunate  persons  becoming  saturated  with  the 
inflammable  properties  of  the  alcohol  thus  taken  into  the 

&O.  The  regulation  of  the  temperature  of  the  body.     Give  the  explanation. 
51)  52.  State  what  is  said  of  spontaneous  combustion. 


146  RESPIRATION. 


system,  took  fire  upon  being  exposed  to  a  flame,  as  of  a 
lighted  candle,  or,  indeed,  without  any  external  cause.  But, 
whether  this  be  possible  or  not,  one  thing  is  certain,  this 
strange  kind  of  combustion  has  never  been  actually  wit- 
nessed by  any  one  competent  to  give  a  satisfactory  account 
of  it. 

52.  The  results  that  have  been  observed  may  be  satis- 
factorily explained  by  the  accidental  ignition  of  the  clothes, 
or  other  articles  near  the  body,  and  by  the  supposition 
that  the  individual  was  at  the  time  too  much  stupefied  by 
intoxication,  to  notice  the  source  of  danger,  and  provide 
for  his  safety.  The  highest  temperature  that  has  been 
observed  in  the  body,  about  112°  Fahrenheit,  is  too  low 
to  ignite  the  vapor  of  alcohol;  much  less  will  it  cause 
the  burning  of  animal  tissues.  It  is  undoubtedly  true 
that  when  the  tissues  are  filled  with  alcohol,  combus- 
tion will  more  easily  take  place  than  when  the  body  is  in 
a  normal  state ;  but,  under  any  condition,  the  combustion 
of  the  body  requires  a  higher  degree  of  heat  than  can  be 
generated  by  the  body  itself,  or  the  mere  proximity  of  a 
lighted  candle,  or  any  cause  of  a  similar  character. 


REVIEW    QUESTIONS.  147 


QUESTIONS  FOR  TOPICAL  REVIEW. 

PAGE 

1.  What  is  the  object  of  respiration  ? 123 

2.  What  are  the  special  organs  of  respiration  ? 123 

3.  In  what  organ?  do  s  a  change  in  the  blood  take  place  ? 123 

4.  What  is  the  nature  of  the  change  ? 123,  133 

5.  Where  are  the  lungs  situated,  and  what  is  the  character  of  the  sub- 

stance of  which  they  are  composed  ? 123,  125 

6.  Describe  the  facilities  provided  for  the  lung  movements 124 

7.  Describe  the  trachea,  or  windpipe.   124,  125,  127,  128 

8.  Describe  the  bronchial  tubes,  and  their  uses 125,  126 

9.  What  can  you  state  in  relation  to  the  epiglottis  ' 1-26,  127 

10.  What  are  the  cilia  and  what  use  do  they  probably  serve  ? 128 

11.  How  may  the  lungs  be  affected  by  not  being  properly  protected  ? 128 

12.  Describe  the  movements  necessary  to  the  act  of  perfect  respiration. . .  128,  129 

13.  What  is  the  diaphragm,  and  what  is  its  office? 128,  129 

14.  How  may  the  organs  of  respiration  be  so  improved  as  to  increase  their 

capacity  and  power  ? 129,  37 

15.  What  is  stated  in  relation  to  the  frequency  of  respiration  ? 129,  130 

10.  To  what  extent  may  the  act  of  respiration  be  subjected  to  our  wills  ? 130 

17.  What  may  be  said  to  be  the  capacity  of  the  lungs  ? 130,  131 

18.  How  long  does  it  take  every  particle  of  air  in  the  lungs  to  be  expelled  and 

new  air  to  take  its  place  ? 130 

19.  What  would  be  the  consequences,  if  the  entire  capacity  of  the  lungs 

were  constantly  used  ? 130,  131 

20.  What  would  be  the  consequences  to  a  fish  put  into  water  from  which  the 

air  had  been  completely  exhausted  ?    Why  ? 131 

21.  What  is  the  air,  and  what  are  its  parts  ? 131,  136,  138 

22.  What,  is  the  character  of  the  air  that  has  been  just  breathed  ? 132 

23.  Why  is  it  that  such  air  is  not  fit  for  respiration  ? 132,  139 

24.  What  are  the  effects,  as  recorded  in  notable  cases,  of  confinement  in  places 

the  air  of  which  has  been  breathed  "  over  an  ,  over  ?" 133 

25.  What  can  you  state  of  changes  in  the  blood  from  respiration  ?  . 133 

26.  What  of  the  air,  as  an  article  of  food  ? 133,  134 

27.  What,  on  the  subject  of  interchange  of  gases  in  the  lungs  ? 134 

28.  Explain  the  difference  between  arterial  and  venous  blood 134,  135 

29.  Explain,  if  you  can,  the  cau-e  of  the  difference 135 

30.  State  what  you  can  in  relation  to  blue  blood 135 

31 .  In  relation  to  the  amount  of  labor  exerted  in  respiration 135,  136 

32.  In  relation  to  the  deleterious  properties  of  different  gases 136,  137 

33.  In  relation  to  the  dust  that  floats  in  the  air 137,  138 

34.  What  are  the  properties  of  carbonic  acid  gas  ? 132,  138,  141 

35.  In  what  places  is  carbonic  acid  gas  commonly  found  ? 132,  138,  139 

36.  Describe  the  effects  of  carbonic  acid  gas 132,  128,  139,  141 

37.  What  are  the  general  effects  of  breathing  any  impure  atmosphere  ? . . . .  139, 140 

38    What  are  Nature's  provisions  for  purifying  the  air? 141,  142 

3f».  What  hints  and  directions  are  given  on  the  subject,  of  ventilation  ?. . . .  142,  143 

40.  How  does  the  temperature  of  the  body  compare  with  the  medium  in  which 

it  lives? 143 

41.  How  is  temperature  of  the  body  regulated  and  sustained  ? 143, 144,  145 

42.  State  what  you  can  on  the  subject  of  spontaneous  combustion 145,  146 


148  THE   tfEKVOUS   SYSTEM. 


CHAPTER  IX. 
THE  NERVOUS  SYSTEM. 

Animal  and  Vegetative  Functions — Sensation,  Motion,  and  Volition — 
The  Structure  of  the  Nervous  System — The  White  and  Gray  Sub- 
stances— The  Brain — Its  Convolutions — The  Cerebellum — The  Spi- 
nal Cord  andf  its  System  of  Nerves— The  Anterior  and  Posterior 
Roots — The  Sympathetic  System  of  Nerves — The  Properties  of  Nerv- 
ous Tissue — Excitability  of  Nervous  Tissues — The  Functions  of  the 
Spinal  Nerves  and  Cord — The  Direction  of  the  Fibres  of  the  Cord — 
Reflex  Activity,  and  its  Uses— The  Functions  of  the  Medulla  Oblon- 
gata  and  the  Cranial  Ganglia — The  Reflex  Action  of  the  Brain. 

1.  Animal  Functions. — The  vital  processes  which  we 
have  been  considering,  in  the  three  previous  chapters,  of 
digestion,  circulation,  and  respiration — belong  to  the  class 
of  functions  known  as  vegetative  functions.     That  is,  they 
are   common   to  vegetables  as  well   as  animals;   for  the 
plant,  like  the  animal,  can   originate   nothing,  not  even 
the  smallest  particle  of  matter;  and  yet  it  grows,  blossoms, 
and  bears  fruit,  by  reason  of  obtaining  and  digesting  the 
nutriment  which  the  air  and  soil  provide.     The  plant  has 
its  circulatory  fluid  and  channels,  by  which  the  nutriment 
is  distributed  to  all  its  parts.     It  has,  also,  a  curious  ap- 
paratus in  its  foliage,  by  which  it  abstracts  from  the  air 
those  gaseous  elements  so  necessary  to  its  support;  and 
thus  it  accomplishes  vegetable  respiration.     These  vege- 
tative functions  have  their  beginning  and  end  within  the 
organism  of  the  plant;  and  their  object  is  the  preservation 
of  the  plant  itself,  as  well  as  of  the  entire  species. 

2.  The  animal,  in  addition  to  these  vegetative  functions, 
has  another  set  of  powers,  by  the  use  of  which  he  becomes 
conscious  of  a  world  external  to  himself,  and  brings  him- 

1.  What  processes  are  known  as  the  vegetative  functions?    Why  so  called? 
What  properties  and  functions  does  the  plant  possess  ?    Their  object  ? 

2.  What  second  set  of  powers  has  the  animal  ?    What  functions  are  mentioned ': 
The  advantage  they  give  ? 


THE   NERVOUS   SYSTEM.  149 

self  into  active  relations  with  it.  By  means  of  the  vege- 
tative processes,  his  life  and  species  are  maintained;  while, 
by  means  of  certain  animal  functions,  he  feels,  acts;  and 
thinks.  These  functions,  among  which  are  sensation, 
motion,  and  volition,  not  only  distinguish  the  animal  from 
the  plant,  but,  in  proportion  to  their  development,  elevate 
one  creature  above  another ;  and  it  is  by  virtue  of  his  pre- 
eminent endowment,  in  these  respects,  that  man  holds  his 
position  at  the  head  of  the  animal  creation. 

3.  Among  animals  whose  structure  is  very  simple,  the 
hydra,  or  fresh- water  polyp,  being  an  example,  no  special 
organs  are  empowered  to  perform  separate  functions ;  but 
every  part  is  endowed  alike,  so  that  if  the  animal  be  cut 
into  pieces,  each  portion  has  all  the  properties  of  the  entire 
original;  and,  if  the  circumstances  be  favorable,  each  of 
the  pieces  will  soon  become  a  complete  hydra.    As  we  ap- 
proach man,  in  the  scale  of  beings,  we  find  that  the  orgaifs 
multiply,  and  the  functions  become  more  complete.     The 
function  of  motion,  the  instruments  of  which— the  muscles 
and  bones— have  been  considered  in  former  chapters,  and 
all  the  other  animal  functions  of  man,  depend  upon  the  set 
of  organs  known  as  the  nervous  system. 

4.  The  Nervous   System. — The  intimate  structure 
of  this  system  differs  from  any  tissue  which  we  have  be- 
fore examined.     It  is  composed  of  a  soft,  pulpy  substance, 
which,  early  in  life,  is  almost  fluid,  hut  which  gradually 
hardens  with  the  growth  of  the  body.     When  examined 
under  the  microscope,  it  is  found  to  be  composed  of  two 
distinct   elements: — (1)  the   white   substance,  composing 
the  larger  proportion  of  the  nervous  organs  of  the  body, 
which  is  formed  of  delicate  cylindrical  filaments,  about 
-g-jJL-  of  an  inch  in  diameter,  termed  the  nerve-fibres ;  and 
(2)  the  gray  substance,  composed  of  grayish-red,  or  ashen- 

3.  Animals  whose  structure  is  simple?    As  we  approach  man?    Dependence 
of  the  animal  functions  of  man  ? 

4.  The  nervous  tissues,  of  what  composed  ?     When  examined  by  the  aid  of  the 
microscope  ?    The  white  substance  ?    The  gray  substance  ? 


150  THE   NERVOUS   SYSTEM. 

colored  cells,  of  various  sizes,  generally  possessing  one  or 
more  off-shoots,  which  are  continuous  with  the  nerve- 
fibres  just  mentioned. 

5.  The  gray,  cellular  substance  constitutes  the  larger 
portion  of  those  important  masses,  which  bear  the  name  of 
nervous  centres  and  ganglia  (from  ganglion,  a  knot),  and 
in  which  all  the  nerve-fibres  unite.     These  white  nerve- 
fibres  are  found   combined   together  in   long   and  dense 
cords,  called  nerves  (from  neuron,  a  cord),  which  serve  to 
connect  the  nervous  centres  with  each  other,  and  to  place 
them  in  communication  with  all  the  other  parts  of  the 
body  which  have  sensibility  or  power  of  motion.      That 
part  of  the  nervous  system  which  is  concerned  in  the  ani- 
mal functions,  comprises  the  brain,  the  spinal  cord,  and  the 
nerves  which  are  derived  therefrom;  these  are,  together, 
called  the  cerebro-spinal  system  (Fig.  40) ;  while  that  other 
set  of  organs,  which  presides  over,  and  regulates  the  vege- 
tative functions,  is  called  the  sympathetic  system  of  nerves. 

6.  The  Brain. — The  brain  is  the  great  volume  of  nerv- 
ous tissue  that  is  lodged  within  the  skull.     It  is  the  largest 
and  most  complex  of  the  nervous  centres,  its  weight,  in  the 
adult,  being  about  fifty  ounces,  or  one-fortieth  of  that  of 
the  whole  body.     The  shape  of  the  brain  is  oval,  or  egg- 
shaped,  with  one  extremity  larger  than  the  other,  which  is 
placed  posteriorly  in  the  skull,  to  the  concavity  of  which  it 
very  closely  conforms.     The  brain  consists  chiefly  of  two 
parts;  the  cerebrum,  or  brain  proper,  and  the  cerebellum, 
or  "little  brain."     In  addition  to  these,  there  are  several 
smaller  organs  at  the  base,  among  which  is  the  commence- 
ment or  expansion  of  the  spinal  cord,  termed  the  medulla 
oUongata9  or  oblong  marrow. 

7.  The  tissue  of  the  brain  is  soft  and  easily  altered  in 

5.  Nervous  centres  and  ganglia?     Nerves?     What  do  they  serve?     Cerebro- 
epinal  system? 

6.  Location  of  the  brain  ?    Its  weight  ?    Its  shape  ?    Of  what  it  consists  ?  What 
or-ran*  at  the  base  ? 

7.  The  tissue  of  the  brain  ?    What,  therefore,  is  required  ?    Blows  on  the  head  ? 
Membranes  of  the  brain  ?     Blood  sent  to  the  brain  ? 


THE   NERVOUS   SYSTEM. 


151 


FIG.  40.— THK  CEREBRO-SPINAI,  SYSTEM. 


152  THE   NERVOUS   SYSTEM. 

shape  by  pressure;  it  therefore  requires  to  be  placed  in  a 
well-protected  position,  such  as  is  afforded  by  the  skull,  or 
cranium,  which  is  strong  without  being  cumbrous.  In 
the  course  of  an  ordinary  lifetime,  this  bony  box  sustains 
many  blows,  with  little  inconvenience;  while',  if  they  fell 
directly  upon  the  brain,  they  would  at  once,  and  com- 
pletely, disorganize  that  structure.  Within  the  skull,  the 
brain  is  enveloped  by  certain  membranes,  which  at  once 
protect  it  from  friction,  and  furnish  it  with  a  supply  of 
nutrient  vessels ;  they  are  called  the  arachnoid,  or  "spiders 
web,"  the  dura  mater  and  the  pia  mater,  or  the  "tough" 
and  "delicate  coverings."  The  supply  of  blood  sent  to 
the  brain  is  very  liberal,  amounting  to  one-fifth  of  all 
that  the  entire  body  possesses.  The  brain  of  man  is 
heavier  than  that  of  any  other  animal,  except  the  ele- 
phant and  whale. 

8.  The  Cerebrum. — The  brain  proper,  or  cerebrum,  is 
the  largest  of  the  intracranial  organs,  and  occupies  the  en- 
tire upper  and  front  portion  of  the  skull.   It  is  almost  com- 
pletely bisected,  by  a  fissure,  or  cleft,  running  through  it 
lengthwise,  into  two  equal  parts  called  hemispheres.     The 
exterior  of  these  hemispheres  is  gray  in  color,  consisting 
chiefly  of  nerve-cells,  arranged  so  as  to  form  a  layer  of  gray 
matter  one-fifth  of  an  inch  in  thickness,  and  is  abundantly 
supplied  with  blood-vessels.      The  interior  of  the  brain, 
however,  is  composed  almost  wholly  of  white  substance,  or 
nerve-fibres. 

9.  The  surface  of  the  cerebrum  is  divided  by  a  consid- 
erable number  of  tortuous  and   irregular  furrows,  about 
an  inch  deep,' into  "convolutions,"  as  shown  in  Fig.  41. 
Into  these  furrows  the  gray  matter  of  the  surface  is  ex- 
tended, and,  in  this   manner,  its   quantity  is  vastly  in- 
creased.    The  extent  of  the  entire  surface  of  the  brain, 

8.  Size  of  the  brain  proper?     How  divided?    The  exterior  of  the  hemispheres? 
The  interior  ? 

9.  The  surface  of  the  cerebrum,  how  marked  ?    The  gray  matter  of  the  surface  ? 
Extent  of  the  entire  brain  surface  ?    Source  of  nervous  power  ?    What  further  ? 


THE-  NERVOUS  SYSTEM. 


153 


•with  the  convolutions  unfolded,  is'cornputed  to  be  equal  to 
four  square  feet;  and  yet  it  is  easily  enclosed  within  the 
narrow  limits  of  the 
skull.  When  it  is 
stated  that  the  gray 
matter  is  the'  true 
source  of  nervous 
power,  it  becomes 
evident  that  this 
arrangement  has  an 
important  bearing 
on  the  mental  ca- 
pacity of  the  indi- 
vidual. And  it  is 
noticed  that  in 
children,  before  the 
mind  is  brought 
into  vigorous  use, 
these  markings  or 
furrows  on  the  sur- 
face are  compara- 
tively shallow  and 
indistinct;  the  same  fact  is  true  of  the  brain  in  the  less 
civilized  races  of  mankind  and  in  the  lower  animals.  It  is 
also  noticeable,  that  among  animals,  those  are  the  most 
capable  of  being  educated  which  have  the  best  develop- 
ment of  the  cerebrum. 

10.  The  Cerebellum.— The  "little  brain"  is  placed 
beneath  the  posterior  part  of  the  cerebrum,  and,  like  the 
latter,  is  divided  into  hemispheres.  Like  it,  also,  the  sur- 
face of  the  cerebellum  is  composed  of  gray  matter,  and  its 
interior  is  chiefly  white  matter.  It  has,  however,  no  con- 
volutions, but  is  subdivided  by  many  crescentic,  parallel 
ridges,  which,  sending  down  gray  matter  deeply  into  the 


-II.— Ui'PKK  SURFACE  OF  THE  CEREBRUM. 


A,  Longitudinal  Fissure. 

B,  The  Hemispheres. 


10.  Location  of  the  "  little  brain  ?' 
Its  subdivisions  ?    Its  size  ? 


How  divided  ?    Its  surface  and  interior  ? 

7* 


154  THE   NERVOUS   SYSTEM. 

white,  central  portion,  gives  the  latter  a  some  what  branched 
appearance.      This   peculiar    appearance  lias  been   called 


FIG.  42.— VERTICAL  SECTION  OF  THE  BRAIN. 

A,  Left  Hemisphere  of  Cerebrum.  D,  The  Pons  Varolii. 

B,  Corpus  Callosum.  E,  Upper  extremity  of  the  Spinal  Cora, 

C,  Optic  Thalamup.  F,  The  Arbor  Vitae. 

the  arbor  vitce,  or  the  "  tree  of  life,"  from  the  fact  that 
when  a  section  of  the  organ  is  made,  it  bears  some  resem- 
blance to  the  trunk  and  branches  of  a  tree  (Fig.  42,  F). 
In  size,  this  cerebellum,  or  "little  brain,"  is  less  than  one- 
eighth  of  the  cerebrum. 

11.  From  the  under  surface  of  the  cerebrum,  and  from 
the  front  margin  of  the  cerebellum,  fibres  collect  together 
to  form  the  medulla  oUongata  (Fig.  43,  MA),  which,  on  is- 
suing from  the  skull,  enters  the  spinal  column,  and  then 
becomes  known  as  the  spinal  cord.  From  the  base  of  the 
brain,  and  from  the  sides  of  the  medulla  originate,  also, 
the  cranial  nerves,  of  which  there  are  twelve  pairs.  These 
nerves  are  round  cords  of  glistening  white  appearance,  and, 

4 

11.  Medulla  oblongata?    Cranial  nerves?    Their  shape  and  position  ? 


THE   NERVOUS   SYSTEM.  155 

like  the  arteries,  generally  lie  remote  from  the  surface  of 
the  body,  and  are  well  protected  from  injury. 


FIG.  13.— THE  BASE  OF  THE  BRAIN. 

12.  The  Spinal  Cord. — The  spinal  cord,  or  "marrow," 
is  a  cylindrical  mass  of  soft  nervous  tissue,  which  occupies 
a  chamber,  or  tunnel,  fashioned  for  it  in  the  spinal  column 
(Fig.  44).     It  is  composed  of  the  same  substances  as  the 
brain  ;  but  the  arrangement  is  exactly  reversed,  the  white 
matter  encompassing  or  surrounding  the  gray  matter  in- 
stead of  being  encompassed  by  it.      The  amount  of  the 
white  substance  is  also  greatly  in  excess  of  the  other  ma- 
terial.    A  vertical  fissure  partly  separates  the  cord  into 
•two  lateral  halves,  and  each  half  is  composed  of  two  sep- 
arate bundles  of  fibres,  which  are  named  the  anterior  and 
posterior  columns. 

13.  These  columns  have  entirelv  different  uses,  and  each 


12.  The  spinal  cord  ?    Of  what  composed  ?    How  divided  ?    Each  half? 

13.  Uses  of  these  columns  ?    Importance  of  this  part  of  the  nervous  system  ? 
How  protected? 


15G 


THE   NERVOUS   SYSTEM. 


FIG.  44. 

A,  Cerebrum. 

B,  Cerebellum. 

D,  D.  Spinal  Cord. 


of  them  unites  with  a  different 
portion  of  the  nerves  which  have 
their  origin  in  the  spinal  cord. 
The  importance  of  this  part  of 
the  nervous  system  is  apparent 
from  the  extreme  care  taken  to 
protect  it  from  external  injury. 
For,  while  a  very  slight  disturb- 
ance of  its  structure  suffices  to 
disarm  it  of  its  power,  yet  so 
staunch  is  its  bony  enclosure, 
that  only  by  very  severe  injuries 
is  it  put  in  peril.  The  three 
membranes  that  cover  the  brain 
are  continued  downward  so  as 
to  envelope  and  still  further 
shield  this  delicate  organism. 

14.  The  Spinal  Nerves.— 
The  spinal-  nerves,  thirty- one 
pairs  in  number,  spring  from 
each  side  of  the  cord  by  two 
roots,  an  anterior  and  a  poste- 
rior root,  which  have  the  same 
functions  as  the  columns  bear- 
ing similar  names.  The  poste- 
rior root  is  distinguished  by  pos- 
sessing a  ganglion  of  gray  mat- 
ter, and  by  a  somewhat  larger 
size.  The  successive  points  of 
departure,  or  the  oif-shooting  of 
these  nerves,  occur  at  short  and 
nearly  regular  intervals  along 
the  course  of  the  spinal  cord. 
Soon  after  leaving  these  points, 


14.  The  spinal  nerves?    The  posterior  root?    The  nerves,  how  arranged: 
"heir  office  ? 


THE   NERVOUS   SYSTEM.  157 


the  anterior  and  posterior  roots  unite  to  form  the  trunk 
of  a  nerve,  which  is  distributed,  by  means  of  branches, 
to  the  various  organs  of  that  part  of  the  body  which  this 
nerve  is  designed  to  serve.  The  spinal  nerves  supply 
chiefly  the  muscles  of  the  trunk  and  limbs  and  the  ex- 
ternal surface  of  the  body. 

15.  The  tissue  composing  the  nerves  is  entirely  of  the 
white  variety,  or,  in   other  words,  the   nerve-fibres ;    the 
same  as  we  have  observed  forming  a  part  of  the  brain. 
But  the  nerves,  instead  of  being  soft  and  pulpy,  as  in  the 
case  of  the  brain,  are  dense  in  structure,  being  hardened 
and  strengthened  by  means  of  a  fibrous  tissue  which  sur- 
rounds each  of  these  delicate  fibres,  and  binds  them  to- 
gether in  glistening,  silvery  bundles.     Delicate  and   mi- 
nutely fine  as  are  these  nerve-fibres,  it  is  probable   that 
each  of  them  pursues  an  unbroken,  isolated  course,  from  its 
origin,  in  the  brain  or  elsewhere,  to  that  particular  point 
which  it  is  intended  to  serve.     For,  although  their  extrem- 
ities are  often  only  a  hair's  breadth  distant  from  each  other, 
the  impression  which  any  one  of  them  communicates  is 
perfectly  distinct,  and  is  referred  to  the  exact  point  whence 
it  came. 

16.  This  may  be  illustrated  in  a  simple  manner,  thus: 
if  two  fingers  be  pressed  closely  together,  and  the  point  of  a 
pin  be  carried  lightly  across  from  one  to  the  other,  the  eyes 
may  be  closed,  and  yet  we  can  easily  note  the  precise  instant 
when  the  pin  passes  from  one  finger  to  the  other.     If  the 
nerve-fibres  were  less  independent,  and  if  it  were  necessary 
that  they  should  blend  with  and  support  each  other,  all 
accuracy  of  perception  would  be  lost,  and  all  information 
thus  afforded  would  be  pointless  and  confused.     These  sil- 
very threads  must,  therefore,  be  spun  out  with  an  infinite 
degree  of  nicety.    Imagine,  for  instance,  the  fibre  which 


1 5.  The  nerve  tissue  ?    Its  character  ?    Course  of  each  nerve  fibre  ? 

1 6.  How  may  we  illustrate  the  fact  ?     The  fibre  connecting  the  brain  with  a 
point  in  the  foot  ? 


158  THE    NERVOUS    SYSTEM. 

connects  the  brain  with  some  point  on  the  foot, — its  length 
cannot  be  less  than  one  hundred  thousand  times  greater 
than  its  diameter;  and  yet  it  performs  its  work  with  as 
much  precision  as  fibres  that  are  comparatively  much 
stronger  and  less  exposed. 

17.  The   Sympathetic   System. — The    sympathetic 
system,  of  nerves  remains  to  be  described.     It  consists  of  a 
double   chain   of  ganglia,  situated   on   each   side   of  the 
spinal  column,  and  extending  through  the  cavities  of  the 
trunk,  and  along  the  neck  into  the  head.     These  ganglia 
are  made  up  for  the  most  part  of  small  collections  of  gray 
nerve-cells,   and    are    the   nerve-centres   of   this   system. 
From   these,  numerous    small   nerves   are  derived,  which 
connect  the  ganglia  together,  send  out   branches  to  the 
cranial  and  spinal  nerves,  and  form  networks  in  the  vicin- 
ity of  the  stomach  and  other  large  organs.    A  considerable 
portion  of  them  also  follows  the  distribution   of  the  large 
and  small  blood-vessels,  in  which  the  muscular  tunic  ap- 
pears.     Branches  also  ascend  into  the  head,  and  supply 
the  muscles  of  the  eye  and  ear,  and  other  organs  of  sense. 

18.  In  this  manner,  the  various  regions  of  the  body  are 
associated  with  each  other  by  a  nervous  apparatus,  which 
is  only  indirectly  connected  with  the  brain   and   spinal 
cord;  and  thus  it  is  arranged  that  the.  most  widely  sep- 
arated  organs  of  the   body  are   brought  into   close  and 
active  sympathy  with  each  other,  so  that,  "if  one  member 
suffers,  all  the  other  members  suffer  with  it."     From  this 
fact,  the  name  sympathetic  system,  or  the  great  sympathetic 
nerve,  has  been  given  to  the  complicated  apparatus  we  have 
briefly  described.     Blushing  and  pallor  are  caused  by  men- 
tal emotions,  as  modesty  and  fear,  which  produce  opposite 
conditions  of  the  capillaries  of  the  face  by  means  of  these 
sympathetic  nerves. 

1 7.  The  sympathetic  system  of  nerves  ?     Of  what  does  it  consist  ? 

18.  Association  of  the  various  regions  of  the  body  ?    If  one  member  suffers  ? 
Blushing  * 


THE   XERVOUS   SYSTEM.  159 


19.  The  Properties  of  Nervous  Tissue.— We  have 
seen  that  in  all  parts  of  this  system,  there  are  only  two 
forms  of  nervous  tissue;  namely,. the  gray  substance  and 
the  white  substance,  so  called  from  their  difference  of  color 
as  seen  by  the  naked  eye;  or  the  nerve-cell,  and  the  nerve- 
fibre,  so  called  from  their  microscopic  appearance.     Now 
these  two  tissues  are  not  commonly  mingled  together,  but 
either  form  separate  organs,  or  distinct  parts  of  the  same 
organs.     This  leads  us  to  the  conclusion  that  their  respec- 
tive uses  are  distinct.     And  this  proves  to  be  the  simple 
fact;  wherever  we  find  the  gray  substance,  we  must  look 
upon  it  as  performing  an  active  part  in  the  system,  that  is,, 
it  originates  nervous  impulses ;  the  white  matter,  on  the 
contrary,  is  a  passive  agent,  and  serves  merely  as  a  con- 
ductor of  nervous  influences.      Accordingly,  the  nervous 
centres,  composed  so  largely  of  the  gray  cells,  are  the  great 
centres  of  power,  and  the  white  fibres  are  simply  the  in- 
struments by  which  the  former  communicate  with  the  near 
and  distant  regions  of  the  body  under  their  control. 

20.  We  may  compare  the  brain,  then,  to  the  capital,  or 
seat  of  government,  while  the  various  ganglia,  including 
the  gray  matter  of  the   cord,  like  so   many  subordinate 
official  posts,  are  invested  with  authority  over  the  outly- 
ing provinces;  and  the  nerves,  with  the  white  matter  of 
the  cord,  are  the  highways  over  which  messages  go  and 
return  between  these  provinces  and  the  local  or  central 
governments.     But  both  forms  of  nervous  tissue  possess 
the  same  vital  property,  called  excitability ;  by  which  term 
is  meant,  that  when  a  nerve-cell  or  fibre  is  stimulated  by 
some  external  agent,  it  is  capable  of  receiving  an  impres- 
sion and  of  being  by  it  excited  into  activity.     A  ray  of 
light,  for  example,  falling  upon  one  extremity  of  a  fibre 
ill  the  eye,  excites  it  throughout  its  whole  length ;  and  its 

1 9.  Properties  of  nervous  tissue  ?    Office  of  the  gray  substance  ?    Of  the  white  ? 
"he  nervous  centres?    White  fibres  ? 

20.  What  comparison  is  made  between  the  brain  and  the  nation's  capitol  ? 
The  vital  property,  excitability  ?    What  example  is  given  ? 


160  THE   NERVOUS   SYSTEM. 

other  extremity,  within  the  brain,  communicating  with  a 
nerve-cell,  the  latter,  in  its  turn,  is  excited,  and  the  sensa- 
tion of  sight  is  produced. 

21.  What   sort  of  change   takes  place   in  the   nervous 
tissue  when   its   excitability   is   aroused,   is   not   known ; 
certainly  none   is  visible.      On  this  account,  it  has  been 
thought  by  some,  that  the  nerve-fibre  acts  after  the  man- 
ner of  a  telegraph  wire :  that  is,  it  transmits  its  messages 
without  undergoing  any  material  change  of  form.     But, 
though  the  comparison  is  a  convenient  one,  it  is  far  from 
being  strictly  applicable ;  and  the  notion  that  nerve-force 
is  identical  with   electricity  has  been  fully  proved  to  be 
incorrect. 

22.  The    Functions  of  the   Nerves. — The  nerves 
are  the  instruments  of  the  two  grand  functions  of  the 
nervous  system,  Sensation  and  Motion.     They  are  not  the 
true  centres  of  either  function,  but  they  are  the  conductors 
of  influences  which  occasion  both.     If  the  nerve  in  a  limb 
of  a  living  animal  be  laid  bare,  and  irritated  by  pinching, 
galvanizing,  or  the  like,  two  results  follow,  namely:  the 
animal  experiences  a  sensation,  that  of  pain,  in  the  part  to 
which  the  nerve  is  distributed,  and  the  limb  is  thrown  into 
convulsive  action.     WJien  a  nerve  in  a  human  body  is  cut 
by  accident,  or  destroyed  by  disease,  the  part  in  which  it 
ramifies  loses  both  sensation  and  power  of  motion ;  or,  in 
other  words,  it  is  paralyzed.     We  accordingly  say  that  the 
nerves  have  a  twofold  use,  a  sensory  and  motor  function. 

23.  If  a  nerve  that  has  been  exposed  be  divided,  and  the 
inner  end,  or  that  still  in  connection  with  the  nerve-cen- 
tres, be  irritated,  sensation  is  produced,  but  no  movement 
takes  place.     But  if  the  outer  end,  or  that  still  connected 
with  the  limb,  be  irritated,  then  no  pain  is  felt,  but  mus- 

*v 

21  •  Change  in  the  nervous  tissues  ?    Nerve  force  and  electricity  ? 

22.  Functions  of  the  nerves  ?    In  the  case  of  the  nerve  of  a  living  animal  ?    Of 
the  human  body  ? 

23,  If  an  exposed  nerve  be  divided?  What  is  proved?  The  course  of  the  sensory 
set  of  fibres  ?    Of  the  motor  set  ?    To  what  are  they  likened  ? 


THE   NERVOUS   SYSTEM.  161, 

cular  contractions  are  produced.  Thus  we  prove  that  there 
are  two  distinct  sets  of  fibres  in  the  nerves ;  one  of  which, 
the  sensory  fibres,  conduct  toward  the  brain,  and  another, 
the  motor  fibres,  conduct  to  the  muscles.  The  former  may 
be  said  to  begin  in  the  skin  and  other  organs,  and  end  in 
the  brain ;  while  the  latter  begin  in  the  nervous  centres 
and  end  in  the  muscles.  They  are  like  a  double  line  of 
telegraph  wires,  one  for  inquiries,  the  other  for  responses. 

24.  We  have  already  spoken  of  the  two  roots  of  the  spinal 
nerves,  called  from   their  points  of  origin  in  the   spinal 
cord,  the  anterior  and  posterior  roots.     These  have  been 
separately  cut  and  irritated  in  the  living  animal,  and  it  has 
been  found  that  the  posterior  root  contains  only  sensory 
fibres,  and  the  anterior  root  has  only  motor  fibres.    So  that 
the  nerves  of  a  limb  may  be  injured  in  such  a  way  that  it 
will  retain  power  of  motion  and  yet  lose  sensation ;  or  the 
reverse  condition,  feeling  without  motion,  may  exist.    Be- 
tween these  two  sorts  of  fibres,  no  difference  of  structure 
can  be  found ;  and  where  they  have  joined  to  form  a  nerve 
it  is  impossible  to  distinguish  one  sort  from  the  other. 

25.  Occasionally  a  nerve  is  so  compressed  as  to  be  tem- 
porarily unable  to  perform  its  functions :  a  transient  par- 
alysis then  takes  place.    This  is  the  case  when  the  leg  or 
arm  "gets  asleep,"  as  it  is  expressed.     When  such  is  the 
condition  with  the  leg,  and  the  person  suddenly  attempts 
to  walk,  he  is  liable  to  fall,  inasmuch  as  the  ,  motor  fibres 
cannot  convey  orders  to  the  muscles  of  the  limb.    Another 
fact  is  observed :  there  is  no  sensation  in  this  nerve  at  the 
point  of  its  compression  ;  but  the  whole  limb  is  numb,  and 
tingling  sensations  are  felt  in  the  foot,  the  point  from 
which  the  sensory  fibres  arise. 

26.  This  illustrates  the  manner  in  which  the  brain  in- 

24.  The  two  roots  of  the  spinal  nerves  ?    What  has  been  found  ?    Difference 
of  the  two  sorts  of  fibres  ?    Result  of  their  union  ? 

25.  Transient  paralysis  ?    When  such  is  the  case  with  the  leg?    What  other 
fact  i  e  observed  ? 

26.  What  does  this  illustrate  ?    Sensation  ?    The  feeling  after  a  limb  has  been 
amputated  ?    Striking  of  the  u  funny  bone  ?" 


162  THE   NERVOUS   SYSTEM. 

terprets  all  injuries  of  the  trunk  of  a  nerve.  Sensation  or 
pain  is  not  felt  at  the  point  of  injury,  but  is  referred  to  the 
outer  extremities  of  the  nerve,  where  impressions  are  habit- 
ually received.  This  is  the  reason  why,  after  a  limb  has 
been  amputated  by  the  surgeon,  the  patient  appears  to 
suffer  pain  in  the  member  that  has  been  severed  from  the 
body ;  while  some  form  of  irritation  at  the  end  of  the  nerve 
in  the  wound,  or  stump,  is  the  real  source  of  his  distress. 
Again,  when  the  "funny-bone" — that  is,  the  ulnar  nerve 
at  the  elbow, — is  accidentally  struck,  the  tingling  sensa- 
tions thus  produced  are  referred  to  the  outer  side  of  the 
hand  and  the  little  finger,  the  parts  to  which  that  nerve  is 
distributed. 

27.  All  the  spinal  nerves,  and  two  from  the  brain,  are 
concerned  in  both  sensation  and  motion.    Of  the  remainder 
of  the  cranial  nerves,  some  are  exclusively  motor,  others 
exclusively  sensory;  and  still  others  convey,  not  ordinary 
sensations,  but  special  impressions,  such  as  sight,  hearing, 
and  smell,  which  we  have  yet  to  consider.     However  much 
the  functions  of  the  nerves  seem  to  vary,  there  is  but  little 
difference  discoverable  in  the  nerves  themselves,  when  ex- 
amined under  the  microscope.     Whatever  difference  exists 
must  be.  accounted  for  in  consequence  of  the  nerves  com- 
municating with  different  portions  of  the  gray  matter  of 
•the  brain.     The  rate  of  motion  of  a  message,  to  or  from 
the  brain  along  a  nerve,  has  been    measured   by  experi- 
ment upon  the  lower  animals,  and  estimated  in  the  case  of 
man  at  about  two  hundred  feet  per  second.    As  compared 
with  that  of  electricity,  this  is  a  very  slow  rate,  but,  in 
respect  to  the  size  of  the  human  body,  it  is  practically  in- 
stantaneous. 

28.  The  Functions  of  the  Spinal  Cord.— As  the 


27.  The  ppinal  nerves,  and  two  from  the  brain  ?  Of  the  remainder?  Difference 
in  the  nerves  ?    How  accounted  for  ?    The  rate  of  conduction  along  a  nerve  ?  As 
compared  with  electricity? 

28.  Function!*  of  the  anterior  and  posterior  column?  of  the  cord  ?    If  the  cord 
be  divided  ? 


THE   NERVOUS   SYSTEM.  163 

anterior  and  posterior  roots  of  the  spinal  nerves  have  sepa- 
rate functions,  so  the  anterior  and  posterior  columns  of 
the  cord  are  distinct  in  function.  The  former  are  con- 
cerned in  the  production  of  motion,  the  latter  in  sensation. 
If  the  cord  be  divided,  as  before  in  the  case  of  the  nerve,  it 
is  found  that  the  parts  below  the  point  of  injury  are  de- 
prived of  sensation  and  of  the  power  of  voluntary  motion 
on  both  sides  of  the  body,  a  form  of  paralysis  which  is 
called  paraplegia. 

29.  This  form  of  disease,  paraplegia,  is  sometimes  seen 
among  men,  generally  as  the  result  of  a  fall,  or  some  other 
severe  accident,  by  which  the  bones  of  the  spine  are  broken, 
and  the  cord  is  crushed,  or  pierced  by  fragments  of  bone. 
The  parts  which  are  supplied  by  nerves  from  the   cord 
above  the  point  of  injury  are  as  sensitive  and  mobile  as 
before.     The  results  are  similar,  whether  the  division  hap- 
pens at  a  higher  or  lower  portion  of  the  spinal  cord ;  but 
the  danger  to  life  increases  proportionally  as  the  injury 
approaches  the  brain.     When  it  occurs  in  the  -neck,  the 
muscles  of  inspiration  are  paralyzed,  since  they  are  sup- 
plied by  nerves  issuing  from  that  region  ;  and  as  a  result 
of  this  paralysis,  the  lungs  are  unable  to  act,  and  life  is 
speedily  brought  to  a  close. 

30.  When  the  spinal  cord  of  an  animal  has  been  cut,  in 
experiment,  it  may  be  irritated  in  a  manner  similar  to  that 
alluded  to  when  considering   the  nerves.      If,  then,  the 
upper  cut  surface  be  excited,  it  is  found  that  pain,  refer- 
able to  the  parts  below  the  cut,  is  produced ;  but  when  the 
lower  cut  surface  is  irritated,  no  feeling  is  manifested.     So 
we  conclude  that  in  respect  to  sensation,  the  spinal  cord  is 
not  its  true  centre,  but  that  it  is  merely  a  conductor,  and 
is  therefore  the  great  sensory  nerve  of  the  body.     When 
the  lower  surface  of  the  cut  is  irritated,  the  muscles  of  the 

29.  Paraplegia?    Result  and  danger  to  life?    When  the  injury  occurs  in  the 
neck? 

30.  Experiment  of  cutting  the  spinal  cord  ot  an  animal  ?    What  inference  is 
drawn? 


164  THE   NERVOUS  SYSTEM. 

parts  below  the  section  are  violently  contracted.  Hence, 
we  conclude  that,  in  respect  to  the  movements  ordered  by 
the  will,  the  spinal  cord  is  not  their  source;  but  that  it 
acts  only  as  a  conductor,  and  is,  accordingly,  the  great 
motor  nerve  of  the  body. 

31.  Direction  of  the  Fibres  of  the  Cord.— If  one 
lateral  half  of  the  spinal  cord  be  cut,  or  injured,  a  very  sin- 
gular fact  is  observed.     All  voluntary  power  over  the  mus- 
cles of  the  corresponding  half  of  the  body  is  lost,  but  the 
sensibility  of  that  side  remains  undiminished.     This  result 
seems  to  show  that  the  motor  fibres  of  the  cord  pursue  a 
direct  course,  while  its  sensory  fibres  are  bent  from  their 
course.     And  this  has  been  proved  to  be  the  fact;  for  im- 
mediately after  the  posterior  roots — the  conductors  of  sen- 
sory impressions — join  the  posterior  columns,  they  enter 
the  gray  matter  of  the  cord,  and  passing  over,  ascend  to  the 
brain  on  the  opposite  side.     Accordingly,  the  sensory  fibres 
from  the  right  and  left  sides  interlace  each  other  in  the 
gray  matter ;  this  arrangement  has  been  termed  the  decus- 
sation,  or  crossing  of  these  fibres.     This  condition  serves 
to  explain  how  a  disease  or  injury  of  the  cord  may  cause  a 
paralysis  of  motion  in  one  leg,  and  a  loss  of  sensation  in 
the  other. 

32.  The  direction  of  the  anterior,  or  motor  columns  of 
the  cord,  is  downward  from  the  brain.     In  the  cord  itself, 
the  course  of  the  motor  fibres  is  for  the  most  part,  a  direct 
one ;  but  in  the  medulla  oblongata,  or  upper  extremity  of 
the  cord,  and  therefore  early  in  their  career,  these  fibres 
decussate,  or  cross  from  side  to  side  in  a  mass ;  and  not 
separately,  as  in  the  case  of  the  posterior  fibres  just  men- 
tioned.    This  arrangement  is  termed  the  decussation  of 
the  anterior  columns  of  the  medulla. 

33.  From   this   double    interlacing   of    fibres  results   a 

3 1 .  What  singular  fact  is  noticed  ?    What  doe?  the  result  show  ? 

32.  Direction  of  the  anterior  or  motor  columns?    In  the  cord  itself?    In  the 
medulla  oblongata  ?    The  decussation  ? 

33.  Result  of  the  double  interlacing  of  fibres?     Where  is  the  seat  of  pain 


THE   NERVOUS   SYSTEM.  165 

crossed  action  between  the  original  and  terminal  extremity 
of  all  nerve-fibres  which  pass  through  the  medulla ; 
namely,  those  of  all  the  spinal  nerves.  Consequently,  if 
the  right  hand  be  hurt,  the  left  side  of  the  brain  feels  the 
pain  ;  and  if  the  left  foot  move,  it  is  the  right  hemisphere 
which  dictates  its  movement.  For  the  same  reason,  when 
a  loss  of  sensation  and  power  of  motion  aifecting  the  right 
side  of  the  body  alone  is  observed,  the  physiologist  under- 
stands that  the  brain  has  been  invaded  by  disease  upon  its 
left  side.  This  affection  is  termed  hemiplegia,  or  the  "  half- 
stroke."  The  full-stroke,  which  often  follows  the  rupture  of 
a  blood-vessel  in  the  brain,  is  commonly  called  paralysis. 

34.  The  Reflex  Action  of  the  Cord. — We  have 
already  considered  the  cord  as  the  great  motor  and  sensory 
nerve  of  the  body,  but  it  has  another  and  extremely  impor- 
tant use.     By  virtue  of  the  gray  matter,  which  occupies 
its  central  portion,  it  plays   the  part  of  an  independent 
nerve  centre.     The  spinal  cord   not   only  conducts  some 
impressions  to  the  brain,  but  it  also  arrests  others;  and,  as 
it  is  expressed,  "  reflects"  them  into  movements  by  its  own 
power.     This  mode  of  nervous  activity  is  denominated  the 
Reflex  Action  of  the  cord. 

35.  A   familiar  example  of  this  power  of  the  cord  is 
found   in  the   violent  movements   which   agitate   a  fowl 
after  its  head  has  been  cut  off.     The  cold-blooded  animals 
also  exhibit  reflex  movements  in  an   astonishing  degree. 
A  decapitated  centipede  will  run  rapidly  forward,  and  will 
seemingly  strive  to  overturn,  or  else  climb  over  obstacles 
placed  in  its  way.     A  frog  similarly  mutilated  will  sustain 
its  headless  body  upon  its  feet,  in  the  standing  posture, 
just  as  it  might  do  if  it  were  still  alive.     If  pushed  over, 
it  will  regain  its  feet ;  and  if  the  feet  are  irritated,  it  will 


when  the  right  hand  is  hurt  ?    The  moving  of  the  foot  ?    Loss  of  sensation  in  one 
side  of  the  body  ? 

34.  What  other  important  use  has  the  cord?    What  is  the  activity  denomi 
nated  ? 

35.  Example  of  the  fowl  ?    Centipede  ?    Prog  ?    What  dc  they  prove  ? 


166  THE   NERVOUS   SYSTEM. 

jump  forward.  There  can  be  no  doubt  that,  in  the  lower 
animals,  movements  may  take  place  which  are  completely 
divorced  from  the  will,  sensation,  and  consciousness;  for 
in  those  animals,  as  well  as  in  man,  these  faculties  have 
Iheir  principal  seat  within  the  brain. 

36.  An  irritation   is  necessary,   in  most  instances,   to 
awaken  reflex  movements.    In  the  case  of  the  decapitated 
fowl,  its  muscles   are    excited  to   convulsive  action    by 
reason  of  its   being  thrown  upon  the  hard  ground  and 
roughly  handled.     Let  it  be  treated   differently,  and  the 
convulsions  will  not  take  place :  let  it  be  laid  gently  upon 
soft  cotton,  and  the  body  will  remain  comparatively  quiet. 
It  may  comfort  some  people  to  know  that  the  convulsions 
which  follow  decapitation  are  not  attended  with  pain  ;  nor 
are  they  a  necessary  part  of  the  "  act  of  death,"  as  some 
suppose. 

37.  In  the  human  body,   likewise,  actions  are  excited 
that  are   entirely   distinct   from   the   ordinary  voluntary 
efforts.     It  is  not  permissible,  desirable,  nor  even  necessary 
to  decapitate  a  man  that  the  body  may  be  disconnected 
from  his  brain,  in  order  to  test  the  effect  of  irritation  upon 
the  spinal  cord;  although  the  bodies  of  beheaded  crimi- 
nals have  been  experimented  upon,  and  caused  to  move  by 
powerful  galvanic  batteries.     The  resort  to  such  means  of 
experiment  is  rendered  unnecessary  by  the  occurrence  of 
certain  deplorable  cases  of  disease  and  injury,  which  effect- 
ually sever  all  communication  between  the  brain  and  a 
large  part  of  the  body. 

38.  Thus,  the  cord  may  be  so  far  injured,  as  the  result 
of  accident,  as  to  terminate  all  sensation  and  voluntary 
motion  in  the  lower  half  of  the  body,  the  patient  seem- 
ingly becoming  lifeless  and  powerless  from  the  waist  down- 
ward.   And  yet,  by  tickling  or  pinching  either  foot,  the  leg 

36.  What  i?  necessary  in  most  cases  to  awaken  reflex  movements?    In  tha 
case  of  the  fowl  ?     Convulsions  which  follow  decapitation  ? 

37.  Actions  in  the  human  body  distinct  from  voluntary  efforts? 

38.  Reflex  action  after  injury'of  the  cord  ?    Why  not'due  to  the  muscles ? 


THE    NERVOUS    SYSTEM.  167 

of  the  same  side  may  be  made  to  jerk,  or  even  to  kick  with 
considerable  force ;  but,  unless  the  patient  is  observing  his 
limbs,  he  is  wholly  unconscious  of  these  movements,  which 
are,  therefore,  performed  independently  of  the  brain.  And 
they  are  in  nowise  due  to  the  muscles  of  the  limb;  for, 
if  the  cord  itself  becomes  diseased  below  the  point  of  in- 
jury, the  muscles  cease  to  contract. 

39.  For  the  production  of  this  form  of  nervous  action 
three  things  are  requisite — (1)  a  nerve  to  conduct  messa- 
ges from  the  surface  of  the  body,  one  of  that  variety  for- 
merly described  as  sensory,  but  which  are  now  incapable  of 
awakening  sensation ;    (2)  a  portion  of  uninjured  spinal 
cord  which  shall  reflect  or  convert  impressions  into  im- 
pulses ;  and  (3)  a  motor  nerve  to  conduct  impulses  outward 
to  the  muscles.     The  power  of  the  cord  to  enforce  reflex 
acts  resides  in  the  gray  matter,  into  which  the  reflex  nerves 
enter  and  from  which  they  depart,  by  means  of  their  pos- 
terior and  anterior  roots  respectively. 

40.  The  Uses  of  the  Reflex  Action.— The  reflex 
activity  of  the  cord  is  exhibited  in  the  healthy  body  in 
many  ways,  but  since  it  is  never  accompanied  with  sensa- 
tion, we  do  not  readily  recognize  it  in  our  own  bodies. 
Reflex  movements  are  best  studied  in  the  cases  of  other 
persons,    when   the   conditions   enable   us  to   distinguish 
between  acts  that  are  consciously,  and  those  that  are  un- 
consciously performed.     For  example,  if  the  foot  of  a  per- 
son soundly,  asleep  be  tickled  or  pinched,  it  will  be  quickly 
withdrawn  from  the  irritation. 

41.  Similar  movements  may  be  observed  in  cases  where 
the  consciousness  and  sensation  are  temporarily  obliter- 
ated by  disease,  or  by  means  of  narcotic  poisons.     If  the 
arm   of  a   person  who  has   been    rendered   insensible  by 


39.  What  arc  lh"  requisites  for  the  production  of  this  form  of  nervous  action? 

40.  Whv  rlo  we  not  readily  recognize  the  reflex  activity  of  the  cord  in  our  own 
bodies  ?     How  best  studied  in  others  ?     Example  ? 

4 1 .  Similar  movements  ?    Arm  of  a  oersou  ?    Melted  wax  or  heated  coin  on  the 
hand? 


168  THE   NERVOUS   SYSTEM. 

chloroform,  be  raised,  and  then  allowed  to  fall,  it  will  be 
noticed  that  the  limb  does  not  drop  instantly,  like  a  life- 
less member,  but  a  certain  amount  of  rigidity  remains  -in 
its  muscles,  which  resists  or  breaks  the  force  of  its  descent. 
Again,  when  a  substance  like  melted  sealing-wax,  or  a 
heated  coin,  falls  upon  the  hand,  the  limb  is  snatched 
away  at  once,  even  before  the  feeling  of  pain  has  been 
recognized  by  the  brain.  When  jolted  in  a  rapidly  moving 
car,  we  involuntarily  step  forward  or  backward,  so  as  to 
preserve  the  centre  of  gravity  of  the  body. 

42.  These  and  similar  acts  are   executed   by  the  same 
mechanism  as  that   previously  described   in  the  case  of 
paralysis  from  an  injury  of  the  spinal  cord.     The  muscles 
thus  called  into  play,  are  those  which  are  ordinarily  under 
the  sway  of  the  will,  but  which  in  these  cases  act  through 
this  reflex  action  of  the  cord,  altogether  independently  of 
the  will.     A  healthful  reflex  activity  produces  an  elasticity, 
or  "  tone,"  of  the  voluntary  muscular  system,  which,  in  a 
great  measure,  explains  the  existence  in  the  young  and 
vigorous  of  a  feeling  of  buoyancy  and  reserve  power.     Its 
possessor  is  restlessly  active,  and  it  may  appropriately  be 
said  of  him,  "he  rejoiceth  as  a  strong  man  to  run  a  race." 
But  this  reflex  energy  may  be  deficient.    This  is  true  when 
the  blood  is  poor  and  wanting  in  its  solid  ingredients,  or 
the  circulation  is  feeble ;  the  muscles,  then,  are  flabby  and 
weak,  and  the  person  himself  is  said  to  be  "  nerveless,"  or 
indisposed  to  exertion.      Shivering  from  cold,  and  trem- 
bling from  fear,  may,  in  part,  be  referred  to  a  temporary 
loss  of  tone,  resulting  from  a  powerful  impression  upon  the 
brain- 

43.  An  excess  of  this  activity  may  also  be  observed  in 
disease.     In  this  condition,  the  excitability  of  the  cord  is 
unnaturally  aroused,  and  frequent  and  violent  movements 

42.  Result  of  healthful  reflex  activity  ?    When  may  the  reflex  energy  he  defl- 

43.  Excess  of  this  activity  in  disease  ?    Hydrophobia,  etc.  ?    The  difference  in 
severity  of  the  convulsions0  " 


THE  NERVOUS  SYSTEM.  169 


of  the  limbs  and  body,  called  convulsions,  are  the  result. 
The  convulsions  of  young  children,  and  the  nervous  agita- 
tion of  chorea,  or  St.  Vitus's  dance,  are  reilex  in  character; 
ag  are  also  the  symptoms  attending  poisoning  by  strychnine, 
and  those  terrible  diseases,  tetanus,  or  "  locked  jaw,"  and 
hydrophobia.  The  severity  of  the  convulsions  is  not  the 
same  in  all  cases  of  these  disorders ;  but.  in  those  last  men- 
tioned the  most  violent  spasmodic  movements  are  provoked 
by  the  slightest  form  of  irritation — such  as  the  sound  of 
pouring  water,  the  sight  of  any  glittering  object,  the  glanc- 
ing of  a  mirror,  the  contact  of  cool  air,  or  even  the  touch 
of  the  bedclothes. 

44.  Another  variety  of  reflex  motions  takes  place  in  cer- 
tain involuntary  muscles,  and  over  these  the  cord  exercises 
supreme  control.     They  are  principally  those  movements 
which  aid  the  performance  of  digestion  and  nutrition,  the 
valve-action  of  the  pylorus,  and  other  movements  of  the 
stomach  and  intestines.     In  these  movements  the   mind 
shares  no  part.     And  it  is  well  that  this  is  so ;  for  since 
the  mind  is  largely  occupied  with  affairs  external  to  the 
body,  it  acts  irregularly,  becomes  fatigued,  and  needs  fre- 
quent rest.     The  spinal  cord,  on  the  contrary,  is  well  fitted 
for  the  form  of  work  on  which  depends  the  growth  and 
support  of  the  body,  as  it  acts  uniformly,  and  with  a  ma- 
chine-like regularity. 

45.  These  operations  are  not  accompanied  by  conscious- 
ness ;  for,  als  a  general  rule,  the  attention  is  only  called  to 
them  when  they  become  disordered.      Many  a  person  does 
not  know  where  his  stomach  is  situated,  until  he  discovers 
its  position  by  reason  of  a  feeling   of  distress  within   it, 
produced  by  giving  that  organ  improper  work  to  perform. 
In  this   manner  the  higher   and  nobler   faculties  of  the 
mind  are  liberated  from  the  simply  routine  duties  of  the 


44.  Another  variety  of  reflex  motions  ?    What  are  they  ?    What  is  stated  of  the 
mind  in  connection  with  these  movements  ? 

45.  Consciousness  in  these  operations?    Physical  wants  ? 

8 


170  THE    NERVOUS    SYSTEM. 

body;  and  we  are  thus  left  to  direct  the  attention,  the  rea- 
son, and  the  will  to  the  accomplishment  of  the  great  ends 
of  our  existence.  If  it  were  otherwise,  wre  could  only  find 
time  to  attend  to  our  ordinary  physical  wants. 

46.  The  objects  of  the  reflex  activity  of  the  cord  are 
threefold.    In  the  first  place,  it  acts  as  the  protector  of  man, 
in  his  unconscious  moments.     It  is  his  unseen  guardian, 
always  ready  to  act,  never  growing  weary,  and  never  re- 
quiring sleep.     Nor  does  its  faithful  action  wholly  cease 
with   the  cessation  of  life  in  other  parts.     In  the  second 
place,  it  is  the  regulator  of  numerous  involuntary  motions 
that  are  necessary  to  the  nutrition  of  the  body.     Here  its 
actions  are  entirely  independent  of  the  brain,  and  are  per- 
formed in  a  secret  and  automatic  manner.     And.  thirdly,  it 
acts  as  a  substitute,  and  regulates  involuntary  movements 
in  the  muscles  usually  under  the  influence  of  the  will.     It 
thus  takes  the  place  of  the  higher  faculties  in  performing 
habitual  acts,  and  permits  them  to  extend  their  operations 
more  and  more  beyond  the  body  and  its  material  wants. 

47.  The  Functions  of  the  Medulla  Oblongata. 
—The  prolongation  of  the  spinal  cord,  within  the  skull, 

has  been  previously  spoken  of  as  the  medulla  oblongata. 
It  resembles  the  cord,  in  being  composed  of  both  white 
and  gray  matter,  and  in  conducting  sensory  and  motor  in- 
fluences. It  likewise  gives  rise  to  certain  nerves,  which  are 
here  called  cranial  nerves  (from  cranium,  the  skull).  All 
except  two  of  these  important  nerves  spring  from  the  me- 
dulla, or  the  parts  immediately  adjoining  it ;  the  exceptions 
are  the  two  nerves  taking  part  in  the  special  senses  of  sight 
and  smell,  which  nerves  have  their  origin  at  the  base  of 
the  cerebrum. 

48.  The  decussation,  or  crossing  of  the  motor  columns, 
has  been  previously  described,  when  treating  of  the  direc- 

46.  How  many  objects  may  the  reflex  activity  be  said  to  have  ?    State  the  first. 
The  second.     The  third. 

47.  How  does  the  medulla  oblongata  resemble  the  cord  ? 

48.  What  final  fact  is  observed  in  the  crossing  of  the  motor  columns  ? 


THE   NERVOUS   SYSTEM.  1?1 

tion  of  the  nerve-fibres  of  the  cord ;  and  the  singular  fact 
has  been  alluded  to,  that  when  one  side  of  the  brain  is 
injured,  its  effects  are  limited  to  the  opposite  side  of  the 
body.  One  more  fact  remains  to  be  observed  in  this  con- 
nection, namely,  this  crossed  action  does  not  usually  take 
place  in  the  cranial  nerves.  Accordingly,  when  apoplexy, 
or  the  rupture  of  a  blood-vessel,  occurs  in  the  right  hemi- 
sphere of  the  cerebrum,  the  left  side  of  the  body  is  paralyzed, 
but  the  right  side  of  the  face  is  affected;  this  is  because 
that  part  of  the  body  is  supplied  by  the  cranial  nerves. 

49.  A  portion  of  the  medulla  presides  over  the  impor- 
tant function  of  respiration,  and  from  it  arises  the  pneu~ 
mogastric  nerve,  so  called  because  its  branches  serve  both 
the  lungs  and  stomach.     The  feelings  of  hunger,  thirst, 
and  the  desire  for  air  are  aroused  by  means  of  this  nerve. 
The  wounding  of  the  gray  matter  of  the  medulla,  even  of 
a  small  portion  of  it,  near  the  origin  of  the  pneumogastric 
nerve,  at  once  stops  the  action  of  the  lungs  and  causes 
death.     In  consequence  of  the  importance  of  this  part,  it 
has  been  termed  the  "vital  knot."     We  find,  also,  that  its 
location  within  the  skull  is  exceedingly  well  protected,  it 
being   quite  beyond   the  reach  of  any  ordinary  form  of 
harm  from  without. 

50.  The  Functions  of  the  Cranial  Ganglia.— The 
uses  of  the  smaller  gray  masses  lying  at  the  basv.   of  the 
brain  are  not  well  ascertained;  and,  on  account  of  their 
position,  so  remote  from  the  surface,  it  would,  at  first,  seem 
well-nigh  impossible  to  study  them.     But,  from  the  results 
following  diseases  in  these  parts,  and   from  experiments 
upon  inferior  animals,  they  are  becoming  gradually  better 
understood;  and  there  is  reason  to  believe  that  eventually 
the  physiological  office  of  each  part  will  be  clearly  ascer- 
tained and  defined.     It  is  believed,  however,  but  not  abso- 


49.  The  pneumogastric  nerve?     The  feelings  aroused  by  it?     The   "vital 
knot?" 

50.  The  uses  of  the  smaller  gray  masses  at  the  base  of  the  brain  ? 


172  THE    NERVOUS    SYSTEM. 


lutely  proven,  that  the  anterior  masses,  like  the  anterior 
roots  of  the  spinal  nerves  and  the  anterior  columns  of 
the  cord,  are  concerned  in  the  production  of  motion;  in 
fact,  that  they  are  the  central  organs  of  that  function. 
The  posterior  gray  masses  are,  on  the  contrary,  supposed 
to  be  the  seat  of  sensation. 

51.  The  Function  of  the  Cerebellum. — The  func- 
tion of  the  cerebellum,  or  "little  brain/'  is  the  direction 
of  the  movements  of  the  voluntary  muscles.     When  this 
organ  is  the  seat  of  disease  or  injury,  it  is  usually  observed 
that  the  person  is  unable  to  execute  orderly  and  regular 
acts,  but  moves  in  a  confused  manner  as  if  in  a  state  of 
intoxication.      Like   the    larger    brain,   or   cerebrum,   it 
appears  to  be  devoid  of  feeling;  but  it  takes  no  part  in 
the  operations  of  the  mind. 

52.  The  Function  of  the   Cerebrum. — The  cere- 
brum, or  brain  proper,  is  the  seat  of  the  mind;  or,  speak- 
ing more  exactly,  it  is  the  material  instrument  by  which 
the  mind  acts;  and,  as  it  occupies  the  highest  position  in 
the   body,   so  it  fulfils   the  loftiest  uses.      All  the  other 
organs  are  subordinate  to  it:* the  senses  are  its  messengers, 
which  bring  it  information  from  the  outer  world,  and  the 
organs  of  motion  are  its  servants,  which  execute  its  com- 
mands.    Here,  as  in  the  nervous  apparatus  of  lower  grade 
already  considered,   the  gray   matter  is  the  element  of 
power;  and,  in  proportion  as  this  substance  increases  in 
extent,  and  in  proportion  to  the  number  of  convolutions 
in  the  hemispheres,  do  the  mental  faculties  expand. 

53.  There  have  been  a  few,  but  only  a  few,  men  of  dis- 
tinguished ability  whose  brains  have  been  comparatively 
small  in  size ;  the  rule  being  that  great  men  possess  large 
brains.     The  relative  weight  of  the  brain  of  man,  as  com- 


5 1 .  Function  of  the  cerebellum  ?    When  it  is  diseased  ? 

52.  Where  is  the  seat  of  the  mind?    The  subordination  of  the  other  organs? 
The  gray  matter  ? 

53.  What  is  stated  of  men  in  connection  with  the  size  of  their  brain  ?    With 
the  brains  of  other  animals  ? 


THE    NEKVOUS    SYSTEM.  173 

pared  with  the  weight  of  the  body,  does  not,  in  all  instan- 
ces, exceed  that  of  the  inferior  animals;  the  canary  and 
other  singing-birds  have  a  greater  relative  amount  of  nerv- 
ous matter  than  man ;  bnt  man  surpasses  all  other  crea- 
tures in  the  size  of  the  hemispheres  of  the  cerebrum,  and 
.in  the  amount  of  gray  substance  which  they  contain. 

54.  It  is  a  singular  fact  that  this  cerebral  substance  is 
insensitive,  and  may  be  cut  without  causing  pain.     The 
removal  of  a  considerable  quantity  of  the  brain  has  taken 
place,  as  the  result  of  accident,  without  causing  death,  and 
without  even  affecting  seriously  the  intellect.     A  remark- 
able  case  of  injury  of  the  brain  is  recorded,  in  which, 
from  the  accidental  explosion  of  gunpowder  used  in  blast- 
ing a  rock,  the  "  tamping-iron"  was  driven  directly  through 
the  skull  of  a  man.     This  iron  rod,  three  feet  and  seven 
inches  long,  an  inch  and  a  quarter  in  diameter,  and  weigh- 
ing more  than  thirteen  pounds,  entered  the  head  below  the 
ear  and  passed  out  at  the  top  of  the  skull,  carrying  with  it 
portions  of  the  brain  and  fragments  of  bone.     The  man 
sustained   the   loss  of  sight  on   one   side,   but  otherwise 
recovered  his  health  and  the  use  of  his  faculties.     More- 
over, disease  has  occurred,  compromising  a  large  portion 
of  the  brain,  without  impairing  the  faculties  of  the  mind, 
when  the  disease  was  limited  to  one  side  only. 

55.  Impressions  conveyed  to  the  hemispheres  from  the 
external    world     arouse     the    mental    operations    called 
thought,   emotion,    and   the   will.      These  are   the  god- 
like  attributes  which   enable  man  to  subjugate  a  world, 
and  afterward  cause  him  to  "  sigh  for  other  worlds  to  con- 
quer;" which  enable   him   to   acquaint  himself  with  the 
properties  of  planets  millions  of  miles  distant  from  him, 
and  which   give   him  that   creative   power   by  which   he 
Guilds  and  peoples  the  new  worlds  of  poetry  and  art. 


54.  Sensitiveness  of  the  brain  substance?     The  removal  of  a  portion  of  the 
train  ?    State  the  remarkable  case  mentioned  ? 

55.  Thought,  emotion,  and  will  ?    What  power  do  they  give  us  ? 


174  THE    NERVOUS   SYSTEM. 

56.  All  these  mental  acts,  and  many  others,  are  devel- 
oped through  the  action  of  the  brain ;  not  that  the  brain 
and   the   mind   are   the  same,  or  that  the  brain  secretes 
memory,  imagination,  or  the  ideas  of  truth  and  justice,  as 
the  stomach  secretes  the  gastric  juice.     But  rather,  as  the 
nerve  of  the  eye,  stimulated  by  the  subtile  waves  of  light, 
occasions  the  notion    of  color,  so  the  brain,  called  into 
action  by  the  mysterious  influences  of  the  immaterial  soul, 
gives  rise  to  all  the  intellectual,  emotional,  and  voluntary 
activities  of  mankind. 

57.  The  cerebrum,  according  to  our  present  knowledge 
of  it,  must  be  regarded  as  a  single  organ,  which  produces 
different  results,  according  as  it  is  acted  upon  by  the  im- 
material mind  in  different  ways.     Recent  investigations, 
however,  seem  to  prove  that  the  faculty  of  language  is  de- 
pendent upon  a  small  part  of  the  left  hemisphere  of  the 
cerebrum,   near   the   temple.     At   least,   in  almost  every 
instance  where  this  part  is  diseased,  the  patient  can  no 
longer  express  himself  in  speech  and  writing. 

58.  The  Reflex  Action  of  the  Brain.— The  reflex 
function  of  the  organs  within  the  skull  is  very  active  and 
important.     Like  that  of  the  cord,  it  protects  the  body  by 
involuntary  movements,  it  regulates  the  so-called  vegeta- 
tive acts,  and  it  takes  the  place  of  the  will  in  controlling 
the  voluntary  muscles,  when  the  attention  is  turned  in 
other  directions.     The  reflex  power  of  the  medulla  governs 
the  acts  of  respiration,  which  are  absolutely  and  continu- 
ously essential  to  life.     Respiration   is,  as  we  have  seen, 
partly  under  the  influence  of  the  will;  but  this  is  due  in 
part  to  the  fact  that  respiration  is  indirectly  concerned  in 
one  of  the  animal  functions,  that  of  speech. 

59.  Reflex  action  also  occasions  coughing  and  sneezing, 

56.  Are  the  brain  and  the  mina  identical? 

57.  What  do  we  know  of  the  cerebrum  and  its  powers  ? 

58.  The  reflex  function  of  the  organs  within  the  skull?    The  reflex  power  oi 
the  medulla  ?    Respiration  ? 

59.  What  else  does  reflex  action  occasion  ?    Winking?    Other  examples  ? 


THE  NERVOUS  SYSTEM.  175 

whenever  improper  substances  enter  the  air-passages. 
Winking  is  an  act  of  the  same  sort,  and  serves  both  to 
shield  the  eyes  from  too  great  glare  of  light,  and  to  pre- 
serve them  by  keeping  the  cornea  moist.  Looking  at  the 
am  or  other  strong  light,  causes  sneezing  by  reflex  action. 
Laughing,  whether  caused  by  tickling  the  feet  or  by  some 
happy  thought,  and  also  sobbing,  are  reflex  acts,  taking 
place  by  means  of  the  respiratory  muscles. 

60.  Certain  of  the  protective  reflex  movements  call  into 
play  a  large  number  of  muscles,  as  in  the  balancing  of  the 
body  when  walking  along  a  narrow  ledge,  or  on  a  slippery 
pavement.     The  dodging  motion  of  the  recruit,  when  the 
first  cannon  ball  passes  over  his  head,  is  reflex -and  invol- 
untary.    The  fact  that  these  involuntary,  reflex  acts  are 
performed  with  great  precision,  will  explain  why  it  is  that 
accidents  seldom  befall  the  somnambulist,  or  sleep-walker, 
although  he  often  ventures  in  most  perilous  places. 

61.  Walking,  sitting,  and   other   acts  of  daily  life,  be- 
come automatic,  or  reflex,  from  habit :  the  mind  is  seldom 
directed  to  them,  but  delegates  their  control  to  the  medulla 
and  spinal  cord.     Thus  a  person  in  walking,  may  traverse 
several  miles  while  absorbed  in  thought,  or  in  argument 
with  a  companion,  and  yet  be  conscious  of  scarcely  one  in 
a  thousand  of  the  acts  that  have  been  necessary  to  carry 
his  body  from  one  point  to  another.     By  this  admirable 
and  .beautiful  provision,  the  mind  is  released  from  the 
charge  of  the  ordinary  mechanical  acts  of  life,  and  may 
devote  itself  to  the  exercise  of  its  nobler  faculties.     And  it 
is  worthy  of  notice,  that  the  greater  the  use  of  these  facul- 
ties, the  more  work  does  the  reflex  function  assume  and 
perform  ;  and  thus  the  employment  of  the  one  insures  the 
improvement  of  the  other. 

60.  Muscles  called  into  play  by  certain  reflex  movements  ?   The  somnambulist  * 

61.  What  is  said  of  walking  and  other  acts  in  connection  with  the  office  per 
formed  by  the  medulla  and  spinal  cord  ? 


176  REVIEW   QUESTIONS. 


QUESTIONS  FOR  TOPICAL  REVIEW. 

PAGE 

1.  State  fully  what  is  meant  by  the  term  vegetable  function 148 

2.  To  what  is  man  indebted  for  his  position  as  the  head  of  the  animal  crea- 

tion ? 148,  149 

3.  What  can  you  state  on  the  subject  of  special  organs  for  separate  functions  ?  149 

4.  Describe,  as  fully  as  you  can,  the  structure  of  the  nervous  system 149,  150 

5.  Describe  the  brain,  its  location,  size,  shape,  and  structure 150.  152 

6.  Describe  the  brain  proper,  or  cerebrum 152,  153,  174 

7.  What   connection   is   noticed    between    the    cerebrum    and   mental 

power  ? 153,  i72, 174 

8.  Describe  the  little  brain,  or  cerebellum 153,  154, 173 

9.  Describe  the  spinal  cord 154,  155, 155 

10.  What  are  the  spinal  nerves,  and  how  are  they  arranged  ? 156, 157 

11.  What  is  the  character  and  substance  of  their  tissues  ? 157 

12.  State  how  the  nerve-fibres  perform  their  office,  and  give  the  illustra- 

tion   157,  158 

13.  Describe  the  sympathetic  system  of  nerves 158 

14.  State  what  is  meant  by  the  properties  of  nervous  tissue,  and  give  the 

illustration 159,  160 

15.  Explain  what  is  meant  by  the  functions  of  the  nerves,  and  give  the 

illustration  160,  101,  162 

16.  What  is  meant  by  a  transient  paralysis  of  a  nerve  ?    Give  the  illustra- 

tion   161,  162 

17.  What  can  you  state  of  the  rate  of  message-motion  along  a  nerve  ? 162 

18.  What  are  the  functions  of  the  spinal  cord  ? 162,  163,  104,  165 

19.  State  what  you  can  of  the  form  of  paralysis  known  as  paraplegia 163 

"20.  What  experiments,  with  results,  upon  the  spinal  cord  are  noted? 163,  164 

21.  Explain  how  injury  of  the  cord  may  produce  paralysis  of  motion  in  one 

leg,  and  at  the  same  time  a  loss  of  sensation  in  the  other 164 

22.  Explain  how,  if  the  right  hand  be  hurt,  the  left  side  of  the  brain  is  made  to 

feel  the  pain 105 

23.  Now,  explain  as  fully  as  you  can  the  direction  of  the  fibres  of  the  cord.  164, 165 

24.  What  is  understood  by  the  reflex  action  of  the  cord  ? 165 

25.  What  experiments  are  mentioned  to  prove  this  power  of  the  cord  ? 165,  160 

26.  What  are  the  uses  of  the  reflex  action  of  the  cord  ? 167-KO 

27.  What  illustrations  are  mentioned  to  show  such  uses  ? 167-170 

28.  What  is  the  medulla  oblongata  ? 154,  170 

29.  What  are  the  functions  of  the  medulla  oblongata  ? 170,  171 

30.  What  can  you  state  of  the  functions  of  the  cranial  ganglia  ? 171,  172 

31.  What  are  the  functions  of  the  cerebellum  ? 172 

32.  What  is  the  function  of  the  cerebrum  ? 172,  174 

33.  In  what  way  does  the  size  of  the  brain  generally  indicate-  the  character 

of  the  man  ? 172,  173 

34.  What  facts  show  that  the  gray  substance  of  the  brain  is  insensitive  * 173 

35.  Upon  what  does  the  faculty  of  language  seem  to  depend  ? 174 

36.  What  has  been  observed  in  support  of  this  statement  ? 174 

37.  Of  what  importance  is  the  reflex  action  of  the  brain  ? 174, 175 

3S.  In  what  ways  is  this  importance  made  manifest  ? 174, 175 


THE    SPECIAL   SENSES.  177 


CHAPTER  X. 

THE   SPECIAL   SENSES. 

The  Production  of  Sensations — Variety  of  Sensations — General  Sensi- 
bility— Pain  and  its  Function — Special  Sensation,  Touch,  Taste, 
Smell,  Sight,  and  Hearing — The  Hand,  the  Organ  of  Touch — TJie 
Sense  of  Touch — Delicacy  of  Touch — Sensation  of  Temperature  and 
Weight— TJie  Tongue  the  Organ  of  Taste— TJie  Nerves  of  Taste— 
The  Sense  of  Taste  and  its  Relations  with  tJie  oilier  Senses — TJie 
Influence  of  Education  on  the  Taste — The  Nasal  Cavities,  or  the 
organs  of  Smell — TJie  Olfactory  Nerve — The  Uses  of  the  Sense  of 
Smell— The  Sense  of  Sight — Light— The  Optic  Nerve— TJie 
Eyeball  and  its  Coverings — The  Function  of  the  Iris — The 
Sclerotic,  Choroid,  and  Retina — The  Tears  and  their  Func- 
tion—  The  Movements  of  the  Eyeball — The  Function  of  Ac- 
commodation—  The  Sense  of  Hearing  and  Sound — The  Ear,  or 
the  organ  of  Hearing — The  External,  Middle,  and  Internal  Ear. 

1.  Production  of    Sensations. — We    have  already 
seen  that  the  true  centre  of  sensation  is  some  organ  within 
the  skull,  probably  among  the  gray  masses  at  the  base  of 
the  brain;  but  the  mind  never  perceives  impressions  at 
that  point ;  but,  on  the  contrary,  always  refers  them  to  the 
external  organs  of  sensation.     Hence,  it  is  convenient  to 
say,  that  those  outer  parts  possess  the  property  of  sensibil- 
ity.   For  instance,  we  say  that  we  hear  with  the  ear,  taste 
with  the  tongue,  and  feel  with  the  fingers.     That  this  is 
not  the  exact  truth  is  proven  by  the  fact,  that  whenever 
the  nerve  connecting  one  of  these  organs  with  the  brain  is 
severed,  it  at  once  loses  its  capacity  for  sensation. 

2.  Consciousness,  another  facujty  of  the  brain,  is  neces- 
sary to  complete  a  sensation.     During  sleep,  and  in  other 
unconscious  states,  the  usual  impressions  are  presented  to 


1 .  True  centre  of  sensation  ?    Place  of  the  mind's  impressions  ?    What  is  it 
convenient  to  say  ?    What  further  is  stated  ? 

2.  Consciousness  ?    During  sleep?    In  profound  insensibility  ? 

S* 


THE   SPECIAL   SENSES. 


the  ear,  the  nose,  and  the  skin,  but  they  fail  to  excite  sen- 
sations, because  the  nerve-centres  are  inactive.  In  pro- 
found insensibility,  from  chloroform  or  ether,  a  limb  may 
be  removed  without  occasioning  the  least  feeling. 

3.  Variety  of  Sensations. — All  animals  have  some 
degree  of  sensibility.     It  is  of  course  feeble  and  indistinct 
in  the  lower  forms  of  life,  but  increases  in  power  and  vari- 
ety as  we  ascend  the  scale.     In  the  earth-worm,  the  nerv- 
ous system  is  very  simple,  the  sensibility  being  moderate 
and  alike  in  all  parts :  hence,  if  its  body  be  cut  into  two 
pieces,  each  piece  will  have  the  same  degree  of  feeling  as 
before.      As  we    approach   man,  however,  the   sensations 
multiply  and  become  more  acute;   the  organs  are  more 
complex,  and  special  parts  are  endowed  with  special  gifts. 
These  special  organs  cannot  be  separated  from  the  rest  of 
the  body  without  the  loss  of  the  functions  they  are  de- 
signed to  exercise. 

4.  The  lowest  form  of  sensation,  that  of  simple  contact, 
is  possessed  by  the  lowest  of  the  animal  creation.     The 
highest  forms  are  those  by  which  we  are  enabled  to  know 
the   properties   of  external   objects,  such   as   shape,  size, 
sound,  and  color.     A  variety  of  means  of  communicating 
with  the  outer  world  is  the  necessary  possession  of  a  high 
intelligence.     Sensations  are  modified  by  use.     They  be- 
some  more  acute  and  powerful  by  moderate  exercise ;  or, 
they   are   dulled   by   undue   excitement.     The  former  is 
shown  by  the  acute  hearing  of  the  Indian,  by  the  sharp 
sight  of  the  sailor,  and  by  the  delicate  touch  of  the  blind. 
The  latter  is  exemplified  by  the  impaired  hearing  of  the 
boiler-maker,  and  the   depraved   taste   of  him  who  uses 
pungent  condiments  with  his  food.      Again,  impressions 
habitually  presented  may  not  be  consciously  felt;    as  is 
the  case  with  the  rumbling  of  carriages  in  a  neighboring 


3.  Sensibility  in  animals  ?    In  the  earth-worm  ?    In  man  ? 

4.  The  lowest  form  of  sensation?    The  highest?    Sensations,  how  modified? 
What  further  can  you  state  as  to  habitual  impressions? 


THE    SPECIAL    SENSES.  170 

street,  or  the  regular  ticking  of  a  clock.  All  sensations 
become  less  vivid  with  the  advance  of  age,  especially  hear- 
ing and  vision. 

5.  General   Sensibility. — There  is  a  property  pos- 
sessed  by  nearly  all  parts  of  the  human  body  which  we 
call  general   sensibility.     We  have  recently  seen  that  the 
brain   is  wholly  insensitive,  and   may  be  cut  or  pinched 
without   pain.     The   same  is  true  of  the  nails,  hair,  the 
Scarf-skin  or  external  covering  of  the  body,  and  a  few  other 
structures.     In  these  parts  no  nerves  are  found.     On  the 
other  hand,  the  sensibility  of  the  true  skin,  and  of  mucous 
membranes,  as  of  the  eye  and  nose,  is  exquisite,  these  or- 
gans having  a  large  supply  of  sensory  nerve-fibres.     The 
bones  and  tendons  have  less  of  these  fibres,  and  are  only 
moderately  sensitive. 

6.  The  sensibility  of  any  part   of  the   body,  then,  de- 
pends upon  the  number  of  nerves  present;  and,  as  a  rule, 
the  nervous  supply  is  proportional  to  the  importance  of 
the  part,  and  to  its  liability  to  injury.     When,  therefore,  a 
surgical  operation  is  performed,  the  most  painful  part  of  it 
is  the  incision  through  the  skin ;  the  muscles,  cartilage, 
and  bone  being  comparatively  without  sensation.     Hence, 
if  we  could  benumb  the  surface,  certain  of  the  lesser  oper- 
ations might  be  undergone  without  great  inconvenience. 
This  is,  in  fact,  very  successfully  accomplished  by  means  of 
the  cold  produced  by  throwing  a  spray  of  ether,  or  of  some 
other  rapidly  evaporating  liquid,  upon  the  part  to  be  cut. 

7.  Tickling  is  a  modification  of  general  sensibility.     At 
first,  it  excites  a  pleasurable  sensation,  but  this  soon  passes 
into  pain.      It.  is  only  present  in  those  parts  where  the 
sense  of  touch   is   feeble.     But   all   impressions   are   not 
received  from   without:   there   are,  also,  certain   internal 


5 .  General  sensibility  ?    What  have  we  seen  as  regards  the  brain  ?    Of  what 
other  structures  is  the  same  true  ? 

6.  The  cause  of  sensibility  ?    Painful  part  in  a  surgical  operation  ?     Benumb- 
ing the  surface  ?    How  done  by  ether  ? 

7.  Tickling  ?    Internal  sensations  ?    The  nerves  of  general  sensibility  ? 


180  THE   SPECIAL   SENSES. 

sensations,  as  they  are  called,  which  depend  upon  the  con- 
dition  of  the  internal  organs,  such  as  appetite,  hunger, 
thirst,  the  sense  of  satisfaction  after  taking  food,  dizziness 
when  looking  down  from  some  lofty  position,  lassitude, 
drowsiness,  fatigue,  and  other  feelings  of  comfort  or  dis- 
comfort. General  sensibility,  whether  of  the  internal  or 
external  organs  of  the  body,  chiefly  depends  upon  the 
sensory  fibres  of  the  spinal  nerve.  The  face,  however,  is 
supplied  by  the  sensory  cranial  nerves.  The  sympathetic 
system  has  a  low  grade  of  feeling  in  health ;  but  disease  in 
the  parts  served  by  it  arouses  an  intense  degree  of  pain. 

8.  The  Sensation  of  Pain.— What  then  is  pain  9    Is 
it  identical  with  ordinary  sensibility  ?     There  seems  to  be 
some  necessary  connection  between  the  two  feelings,  for 
they  take  place  through  the  same  channels,  and  they  are 
alike    intense   in    the   same   situations.      But   sensibility 
habitually  contributes  to  our  sources  of  pleasure,  the  very 
opposite  of  pain ;  hence,  these  feelings  cannot  be  identical. 

9.  Pain  must,  therefore,  be  a  modification  of  the  general 
sensibility,  which  follows  an  excessive  degree  of  excitement 
of  the  nerves ;  there  being  a  natural  limit  to  the  amount  of 
stimulation  which  they  will  sustain.     So  long  as  this  limit 
is  observed,  the  part  excited  may  be  said  to  be  simply  sen- 
sitive; but  when  it  is  exceeded,  the  impression   becomes 
painful.     This  difference  between  sensibility  and  pain  is 
well  shown  by  the  effects  of  sunlight  upon  the  eye.     The 
indirect  illumination  of  the  sun  arouses  only  the  former 
feeling,  and  is  indispensable  to  our  comfort  and  existence ; 
while  the  direct  ray  received  into  the  eye  occasions  great 
pain. 

10.  The  Uses  of  Pain. — The  dread  of  pain  is  a  valu- 
able monitor  to  the  body.     It  puts  us  on  our  guard  in  the 
presence  of  danger;  teaches  moderation  in  the  use  of  our 


8.  Connection  between  pain  and  sensibility? 

9.  Explain  the  difference  between  pain  and  sensibility. 

1O.  Dread  of  pain  *     How  may  its  value  be  appreciated  ?    Example. 


THE   SPECIAL   SENSES.  181 

powers ;  indicates  the  approach  of  disease ;  and  calls  at- 
tention to  it  when  present.  The  word  disease,  in  fact, 
according  to  its  original  use,  had  reference  simply  to  the 
pain,  or  want  of  ease,  which  commonly  attends  disordered 
health.  When  we  observe  the  serious  mishaps  which  occur 
when  sensibility  and  pain  are  absent,  we  cannot  fail  to 
appreciate  its  value.  For  example,  a  paralytic  in  taking  a 
foot-bath,  forgets  to  test  its  temperature,  and  putting  his 
limbs  into  water  while  it  is  too  hot,  is  severely  scalded 
without  knowing  it. 

11.  A  traveller,  overcome  by  cold  and  fatigue,  lies  down 
and  falls  asleep  near  a  large  fire,  and  when  he  is  aroused  in 
the  morning,  it  is  discovered  that  one  of  his  feet  has  been 
insensibly  destroyed.    A  grain  of  sand,  lodging  in  an  insen- 
sitive eye,  may  cause  inflammation  and  even  the  loss  of 
sight.     If  intense  light  were  not  painful  to  the  eye,  many 
a  child  would  innocently  gaze  upon  the  glories  of  the  sun 
to  the  ruin  of  his  sight. 

12.  Pain  is,  indeed,  a  present  evil,  but  its  relations  with 
the  future  prove  its  mission  merciful.    Painful  impressions 
cannot  be  recollected  from  past  experience  ;  and  they  can- 
not be  called  into  existence  by  the  fancy.     Considered  in 
the  light  of  results,  pain  has  a  use  above  that  of  pleasure ; 
for  while  the  immoderate  pursuit  of  the  latter  leads  to 
harm,  the  tendency  of  pain  is  to  restrict  the  hurtful  courses 
of  life,  and  in  this  manner  to  protect  the  body. 

13.  The  relations  of  pain  to  pleasure  are  thus  described 
by  the  eminent  physiologist,  Magendie: — "By  these  sensa- 
tions Nature  induces  us  to  concur  in  the  order  which  she 
has  established  among  organized  beings.     Though  it  may 
appear  like  sophistry  to  say  that  pain  is  the  shadow  of 
pleasure,  yet  it  is  certain  that  those  who'  have  exhausted 
the  ordinary   sources   of  pleasure   have   recourse   to    the 


1 1 .  The  case  of  the  traveller  ?    Grain  of  sand  ?    The  <?nn  and  child  ? 

1 2.  Mission  of  pain  ?  Painful  impressions  compared  with  those  of  pleasure  ? 

13.  What  does  Magendie  say  of  the  relation  of  pain  to  pleasure  ? 


182  THE   SPECIAL   SENSES. 

causes  of  pain,  and  gratify  themselves  by  their  effects.  Do 
we  not  see  in  all  large  cities,  that  men  who  are  debauched 
and  depraved  find  agreeable  sensations,  where  others  ex- 
perience only  intolerable  pain  ?" 

14.  As  to  painful  sensation  among  the  inferior  animals, 
the  plan  of  Nature  seems  to  be,  that  the  higher  the  intel- 
ligence of  the  creature,  and  the  more  complete  its  power 
of  defence,  the  more  acute  is   its  sensibility.     We  infer, 
therefore,  that  animals  low  in  the  scale  of  existence,  and 
helpless,  are  not  very  liable  to  suffer  pain. 

15.  Special    Sensation. — The  sensations  of  simple 
contact  and  pain  are  felt  by  nearly  all  parts  of  the  system, 
whether  external  or  internal,  and  are  the  necessary  con- 
sequence of  the  general  sensibility ;  but,  so  far  as  the  ob- 
jects which  surround  us  are  concerned,  these  impressions 
are  vague  and  passive  in  character,  and  inform  the  mind 
of  none  of  the  properties  or  powers  of  these  objects.     Be- 
sides these  feelings,  therefore,  man  is  endowed  with  certain 
special  sensations,  which  are  positive  and  distinct  in  char- 
acter, and  which  he  can  call  into  exercise  at  will,  and  em- 
ploy in  the  pursuit  of  knowledge.     For  reasons  relating  to 
the  original  constitution  of  the  body,  these  sensations  are 
to  be  regarded  as  modifications  of  the  general  sensibility 
already  alluded  to,  constructed  with  special  reference  to 
the   different   forces   of  Nature,  of  which   we   have   any 
knowledge,  such  as  heat,  motion,  gravity,  sunlight,  and 
the  like. 

16.  These  distinct  and  active  faculties  are  termed  the 
special  senses,  and  are  five  in  number,  viz.,  Touch,  Taste, 
Smell,  Sight,   and  Hearing.      For  the  exercise  of  these 
senses,  special  organs  are  furnished,  such  as  the  hand,  the 
tongue,  the  nose,  the  eye,  and  the  ear.     The  manner  in 
which  the  nerves  of  special  sense  terminate,  varies  in  the 

14.  The  law  of  Nature  as  regards  painful  sensations  among  animals  ? 

15.  The  sensation  of  contact  and  pain?     Special  sensations  of  man?    How 
regarded  ? 

1 6.  What  are  the  special  senses  ?    Special  organs  for  them  ? 


THE   SPECIAL   SENSES.  183 

case  of  each  organ,  so  that  each  is  adapted  to  one  set  of 
sensations  alone,  and  is  incapable  of  perceiving  any  other. 
Thus  the  nerve  of  hearing  is  excited  by  the  undulations  of 
sound,  and  not  by  those  of  light,  while  the  reverse  is  true 
of  the  nerve  of  sight;  and  the  nerve  of  smell  can  appreciate 
neither  of  them,  being  capable  only  of  taking  cognizance 
of  the  odorous  properties  of  bodies. 

17.  By  some  writers  six  senses  are  accorded  to  man  ;  the 
additional  one  being  either  the  sense  of  temperature,  for  as 
we  shall  presently  see  this  is  not  the  same  as  touch;  or 
according  to  others,  the  muscular  sense  by  which  we  are 
enabled  to  estimate  the  weights  of  bodies.     The  latter  also 
differs  in  some  respects  from  the  sense  of  touch. 

18.  Organs  of  Touch. — The   sense  of  touch  is  pos- 
sessed by  nearly  all  portions  of  the  general. surface  of  the 
body,  but  it  finds  its  highest  development  in  the  hands. 
The  human  hand  is  properly  regarded  as  the  model  organ 
of  touch.     The  minute  structure  of  the  skin  fits  it  admi- 
rably for  this  form  of  sensation :  the  cuticle,  or  scarf-skin, 
is  fine  and  flexible,  while  the  outis,  or  true  skin,  contains 
multitudes  of  nerve-filaments,  arranged  in  rows  of  papillm, 
or  cone-like  projections,  about  one-hundredth  of  an  inch  in 
length.   It  is  estimated  that  there  are  20,000  of  these  papillae 
in  a  square  inch  of  the  palmar  surface  of  the  hand.     Now, 
although  the  nerves  of  the  cutis  are  the  instruments  by 
which   impressions  are  received  and   transmitted   to   the 
brain,  yet  the  cuticle  is  essential  to  the  sensation  of  touch. 
This  is  shown  by  the  fact  that  whenever  the  true  skin  is 
laid  bare,  as  by  a  burn  or  blister,  the  only  feeling  that  it 
experiences  from   contact  is  one   of    pain,   not   that  of 
touch. 

19.  The  office  of  the  cuticle  is  thus  made  evident :  it  is 
to  shield  the  nerve  filaments  from  direct  contact  with  ex- 


1 7.  What,  is  said  in  relation  to  one  more  than  the  five  senses  ? 

18.  The  sense  of  touch,  how  prevalent  ?    What  is  said  of  the  hand  ? 

19.  Office  of  the  cuticle  ?    Tips  of  the  fingers  ?    The  fingers  with  thumb  ? 


184  THE   SPECIAL   SENSES. 

fcernal  objects.  At  the  tips  of  the  fingers,  where  touch  is 
most  delicate,  the  skin  rests  upon  a  cushion  of  elastic 
material,  and  receives  firmness  and  permanence  of  shape 
by  means  of  the  nail  placed  upon  the  less  sensitive  side. 
Besides  these  favorable  conditions,  the  form  of  the  arm  is 
such,  and  its  motions  are  so  easy  and  varied,  that  we  are 
able  to  apply  the  test  of  touch  in  a  great  number  of  direc- 
tions. The  slender,  tapering  fingers,  with  their  pliant 
joints,  together  with  the  strong  opposable  thumb,  enable 
the  hand  to  mold  itself  upon  and  grasp  a  great  variety  of 
objects ;  so  that  great  as  are  the  delicacy  and  grace  of  the 
hand,  it  is  not  wanting  in  the  elements  of  power. 

20.  Its  beauty  and  adaptation  to  the  wants  of  man  have 
made   the   hand    an   attractive    theme   for    philosophers. 
They  do  not,  however,  always  agree  in  their  conclusions. 
One  has-  the  opinion  that  man  has  acquired  his  intelligence 
and  achieved  his  place  as  "  lord  of  creation,"  because  he 
has  this  organ.    Buffon,  in  effect,  declares  that  with  fingers 
twice  as  numerous  and  twice  as  long,  we  would  become 
proportionally  wiser;    but  Galen  long  ago  took   a  more 
reasonable  view,  when  he  taught  that  "  man  is  the  wisest 
of  animals,  not  because  he  possesses  the  hand ;  but  because 
he  is  the  wisest  and  understands  its  use,  the  hand  has  been 
given  to  him;  for  his  mind,  not  his  hand  has  taught  him 
the  arts."     Another  has  well  said,  that  "  no  one  can  study 
carefully  the  human  hand  and  fail  to  be  convinced  of  the 
existence  of  the  Deity." 

21.  The  Sense  of  Touch. — Touch  is  the  simplest  of 
the  senses.     It  is  that  which  the  child  first  calls  into  ex- 
ercise in  solving  the  early  problems  of  existence ;  and  it  is 
that  which  is  in  the  most  constant  use  throughout  life. 
We  are  brought  by  the  touch  into  the  most  intimate  rela- 
tions with  external  objects,  and  by  it  we  learn  the  greater 
number,  if  not  the  most  important,  of  the  properties  of 

20.  What  special  importance  is  attributed  to  the  hand? 

2 1 .  The  simplicity  of  touch  ?    What  does  it  teach  us  ? 


THE   SPECIAL   SENSES.  185 

these  objects;    such  as  size,  figure,  solidity,  motion,  and 
smoothness  or  roughness  of  surface. 

22.  The  sense  of  touch  assists  the  other  senses,  especially 
that  of  sight,  giving  foundation  and  reality  to  their  per- 
ceptions.    Without  it,  the  impressions  received  by  the  eye 
would  be  as  vague  and  unreal  as  the  figures  that  float 
through  our  dreams.     A  boy  who   had  been  blind  from 
birth,  at  the  age  of  twelve  years  received  sight  by  means 
of  a  surgical  operation :  at  first,  he  was  unable  to  distinguish 
between  a  globe  and  a  circular  card,  of  the  same  color,  be- 
fore he  had  touched  them.     After  that,  he  at  once  recog- 
nized the  difference  in  their  form.     He  knew  the  peculiari- 
ties of  a  dog  and  a  cat  by  feeling,  but  not  by  sight,  until 
one  day,  happening  to  take  up  the  cat,  he  recognized  the 
connection  of,  the  two  sorts  of  impressions,  those  of  touch 
and  sight ;  and  then,  putting  the  cat  down,  he  said :  "  So, 
puss,  I  shall  know  you  next  time." 

23.  Touch  is  considered  the  least  liable  to  error  of  all 
the  senses ;  yet,  if  that  part  of  the  skin  by  which  the  sense 
is  exercised  is  removed  from  its  customary  position,  a  false 


Fro.  45. 

impression  may  be  created  in  the  mind.  This  is  well  il- 
lustrated by  an  experiment,  which  dates  from  the  time  of 
Aristotle.  If  we  cross  the  middle  finger  behind  the  fore- 

22.  Importance  of  the  sense  of  touch  to  the  development  of  the  other  senses? 

23.  Liability  of  touch  to  err?    Describe  the  illustration. 


186  THE    SPECIAL    SENSES. 

finger,  and  then  roll  a  marble,  or  some  small  object,  upon 
the  tips  of  the  fingers  (see  Fig.  45),  the  impression  will  be 
that  two  marbles  are  felt.  If  the  fingers,  thus  transposed, 
be  applied  to  the  end  of  the  tongue,  two  tongues  will  be 
felt.  When  the  nose  is  accidentally  destroyed,  the  surgeon 
sometimes  performs  an  operation  for  the  purpose  of  form- 
ing a  new  one,  by  transplanting  a  partially  removed  piece 
of  the  skin  of  the  forehead  upon  the  injured  part :  then,  if 
the  new  nose  be  touched  or  pinched,  the  feeling  is  referred 
to  the  forehead.  This  fact  illustrates  one  important  truth, 
that  the  nerves  will  re-unite  after  they  have  been  cut,  and 
feeling  will  be  restored :  if  it  were  otherwise,  a  succession 
of  slight  cuts  upon  the  fingers  would  seriously  impair  their 
tactile  sensibility. 

24.  The  Delicacy  of  Touch. — Although  the  hand 
is  the  proper  organ  of  this  sense,  yet  it  is  exercised  by 
various  parts  of  the  body,  their  degree  of  sensibility  being 
proportional  to  the  number  of  papillae  they  contain.     The 
varying  degrees  of  tactile  delicacy  of  the  different  parts  of 
the  surface  have  been  measured,  in  an  ingenious  manner, 
by  means  of  a  pair  of  compasses,  tipped  with  small  pieces 
of  cork.     The  two  points  of  the  compasses  are  touched  at 
the  same  moment  to  the  skin,  the  eyes  being  closed,  and  it 
is  found  that,  in  sensitive  parts,  the  distance  between  the 
points  maybe  quite  slight,  and  yet  each  be  plainly  felt; 
while,  in  less  sensitive  parts,  the  points  of  the  compasses 
are  felt  as  a  single  point,  although  they  are  separated  one 
or  two  inches. 

25.  At  the  tips  of  the  fingers,  the  distance  between  the 
points  being  one-twentieth  of  an  inch,  a  double  impression 
is  felt.    The  distance  must  be  twice  as  great,  for  the  palm ; 
four  times  as  great,  for  the  lips ;  and,  on  the  forehead,  it 
must  be  twenty  times  greater.     At  the  middle  of  the  back, 
where  the  touch  is  least  acute,  the  points  must  be  sepa- 

24.  The  delicacy  of  tonch  ?    Experiments  with  a  pair  of  compasses  ? 

25.  Further  experiments  and  results  ? 


THE    SPECIAL   SENSES.  187 

rated  more  than  two  inches  before  they  can  be  separately 
felt.  Therefore,  the  sense  of  touch  in  the  fingers  is  said  to 
be  fifty  times  more  delicate  than  upon  the  posterior  sur- 
face of  the  body. 

26.  Exquisite  delicacy  of  touch  is  attained  by  practice. 
This  is  shown  in  many  of  the  lighter  and  more  graceful 
employments  of  daily  life.     Without  it,  the  skill  of  the 
painter,  sculptor,  and  musician  would  be  rude  indeed.    By 
training,  also,  the  physician  acquires  the  tactus  eruditus, 
or  discriminating  touch ;  but  among  the  blind,  delicacy  of 
touch  is  most  remarkable,  and  it  here  finds  its  highest 
value;  for  its  possession,  in  a  measure,  compensates  the 
loss  of  sight  by  enabling  them  to  read,  by  means  of  raised 
letters,  to  work  with  certain  tools,  and  even  to  play  upon 
musical  instruments.     A  person  born  without  sight,  and 
without  hearing  or  voice,  may,  by  the  education  of  the 
touch,  be  rescued  from  apparent  imbecility,  and  be  taught 
not  only  to  read  and  write,  but  even  to  perform  household 
and  other  useful  labors. 

27.  Sensations  of  Temperature   and  Weight.— 
Each  of  these  sensations  has  been  described  by  the  physi- 
ologists as  a  special  sense,  and  they  are  rival  candidates,  so 
to  speak,  for  the  position  and  title  of  the  sixth  sense.    In  the 
sensation  of  temperature,  or  the  thermal  sense,  touch  bears 
a  part,  but  the  two  feelings  appear  to  be  distinct.   In  proof 
of  this,  we  observe,  firstly,  that  they  are  not  alike  intense 
in  the  same  situations ;  as,  for  example,,  the  skin  of  the  face 
and  elbow,  where  the  sense  of  touch  is  feeble,  is  very  sensi- 
tive to  impressions  of  heat  and  cold.     Secondly,  the  ability 
to  recognize  temperature  may  be  lost  by  paralysis,  while 
the   sensibility  of  touch   remains   unaffected.    When   the 
skin  comes  in  contact  with  a  very  hot  substance,  the  sen- 
sation felt  is  that  of  pain,  not  of  touch.     In  like  manner,  a 


26.  Exquisite  delicacy  of  touch  ?    The  same  among  the  blind  ? 

27.  Rival  candidates  for  the  sixth  sense?    Give  the  two  reasons  on  the  sub- 
ject. 


188  THE   SPECIAL   SENSES. 

very  cold  substance  causes  pain,  not  the  feeling  of  cold. 
So  that  a  red-hot  iron,  and  solid  carbonic  acid  (the  tem- 
perature of  which  is  108°  below  zero),  feel  alike ;  and  each, 
if  pressed  slightly,  will  produce  a  blister. 

28.  The  muscular  sense,   by   some   considered   distinct 
from  touch,  gives  rise  to  the  sensations  of  weight,  and 
other   forms   of   external   resistance.      That   this   feeling 
exists,  is  shown  by  the  following  simple  experiment.     If 
the  hand  be   placed  flat  upon  a  table,   and  a  somewhat 
heavy  weight   be   put   into   it,  touch   alone   is   exercised 
and  a  feeling   of  pressure  results;  but  if  the   hand   be 
raised,  a  certain  amount  of  muscular  effort  must  be  put 
forth,   and   thus   the   sensation   of  weight  is  recognized. 
Through  the  muscular  sense,  precision  of  effort  is  rendered 
possible ;  for  by  it  we  learn  to  adjust  the  force  exerted  to 
the  weight  of  the  object  to  be  lifted,  moved,  or  carried. 
Without  it,  all  our  movements  would  necessarily  become 
ill-regulated  and  spasmodic.     In  cases  of  disease,  where  the 
sensibility  of  the  lower  limbs  is  lost,  while  power  of  motion 
remains,  the  patient  is  able  to  stand  erect  so  long  as  he 
can  see  his  limbs;  but  just  as  soon  as  his  eyes  are  closed, 
he  begins  to  waver,  and  will  fall  unless  supported. 

29.  The  Organ  of  Taste.— The  tongue  is  the  special 
organ  of  the  sense  of  taste ;  but  the  back  part  of  the  mouth 
also  possesses   this  faculty.     The  tongue   is   a    muscular 
organ,  the  muscles  composing  it  being  so  numerous  and 
interwoven  as  to  give  it  the  freedom  and  variety  of  motion 
which  it  possesses.     It  can  curve  itself  upward  or  down- 
ward; it  can  extend  or  contract  itself;  and,  with  its  point, 
can  sweep  the  cavity  of  the  mouth,  in  all  directions,  in 
the  search  for  scattered  particles  of  food. 

30.  The  upper  surface  of  the  tongue  is  peculiar,  being 
marked  by  the  presence  of  innumerable  paptffo,  some  of 


28.  The  muscular  sense  ?    State  what  is  paid  to  illustrate  the  subject. 

29.  The  or<ran  of  taste  ?    The  tonprne  ?    Its  powers  of  motion  ? 
ftO.  Peculiarities  of  the  tongue  ?    Uses  of  the  papillae  ? 


THE    SPECIAL   SENSES.  189 

which  are  of  microscopic  size,  resembling  those  that 
abound  in  the  fingers,  and  in  other  parts  of  the  body 
that  have  the  sense  of  touch.  Others  are  much  larger, 
and  give  to  the  tongue  its  roughness  of  feeling  and  ap- 
pearance. Through  the  medium  of  these  papillae,  the 
tongue  receives  impressions  of  touch  and  temperature,  as 
well  as  taste :  indeed,  its  extremity  is  fully  as  delicate,  in 
respect  to  tactile  sensations,  as  the  tips  of  the  fingers  them- 
selves. It  can  recognize  the  two  points  of  the  compasses 
when  separated  not  more  than  one-twenty-fourth  of  an 
inch;  the  back  of  it  is  much  less  sensitive  to  touch,  while 
at  the  same  time  it  is  more  highly  sensitive  to  impressions 
of  taste. 

31.  Each  lateral  half  of  the  tongue  resembles  the  other 
in  structure,  and  each  receives  the  same  number  of  nerves 
— three.     One  of  these  regulates  motion,  the  other  two  are 
nerves  of  special  sense.     One  of  the  latter   supplies  the 
front  half  of  the  tongue,  and  is  called  the  gustatory  nerve. 
This   is  a  branch  of  the   great  cranial  nerve,  called  the 
"fifth  pair,"  which  ramifies  in  all  parts  of  the  face.     The 
back  of  the  tongue  is  endowed  with   the   power  of  taste 
through  a  nerve  known  as  the  glosso-pliaryngeal,  because 
it  is  distributed  both  to  the  tongue  and  throat.     This  dif- 
ference in  the  nervous"  supply  of  the  tongue  becomes  signif- 
icant, when  we  learn,  as  we  shall  presently,  that  each  part 
of  it  perceives  a  different  class  of  flavors. 

32.  The  Sense  of  Taste. — Taste  is  the  special  sense 
by  means  of  which  we  discover  the  savors,  or  flavoring 
properties  of  the  substances,  which*  come  in  contact  with 
the  tongue.     Mere  contact  with  the  surface  of  the  tongue, 
however,  is  not  sufficient,  but  contact  with  the  extremities 
of  the  nerves  of  taste  within  the  papillae  is  required.     In 
order  that  the  substance  to  be  tasted  may  penetrate  the 

3 1 .  Resemblance  fn  the  parts  of  the  tongue  ?    Powers  and  functions  of  thf 
parts  ? 

32.  Taste  ?    What  are  the  requisites  to  taste  ? 


190  THE   SPECIAL   SENSES. 


cells  covering  the  nerves,  it  must  either  be  liquid  in  form, 
or  readily  soluble  in  the  watery  secretion  of  the  mouth, 
the  saliva.  The  tongue  must  be  moist  also.  If  the  sub- 
stance be  insoluble,  as  glass  or  sand,  or  the  tongue  dry,  the 
sense  of  taste  is  not  awakened.  In  sickness,  when  the 
tongue  is  heavily  coated,  the  taste  is  very  defective,  or,  as 
is  frequently  expressed,  "nothing  tastes  aright." 

33.  All  portions  of  the  tongue  are  not  alike  endowed 
with  the  sense  of  taste,  that  function  being  limited  to  the 
posterior  third,  and  to  the  margin  and  tip  of  this  organ. 
The  soft  palate,  also,  possesses  the  sense  of  taste ;  hence, 
an  article  that  has  an  agreeable  flavor  may  very  properly 
be  spoken  of  as  palatable,  as  is  often  done.     All  parts  of 
the  tongue  do  not  perceive  equally  well  the  same  flavors. 
Thus,  the  front  extremity  and  margin,  which  is  the  por- 
tion supplied  by  the  "fifth  pair"  of  nerves,  perceives  more 
acutely  sweet  and  sour  tastes;  but  the  base  of  the  tongue, 
supplied  by  the  glosso-pharyngeal  nerve,  is  especially  sen- 
sitive to  salt  and  bitter  substances.     The  nerve  of  the  front 
part  of  the  tongue,  as  before  stated,  is  in  active  sympathy 
with   those  of  the  face,  while  the  relations  of  the  other 
nerve   are  chiefly  with  the  throat  and  stomach ;  so  that 
when  an  intensely  sour  taste  is  perceived,  the  countenance 
is  involuntarily  distorted,  and  is  said  to  wear  an  acid  ex- 
pression.    On  the  other  hand,  a  very  bitter  taste  affects 
certain  internal  organs,  and  occasions  a  sensation  of  nau- 
sea, or  sickness  of  the  stomach. 

34.  Relations  of   Taste  with    other    Senses.— 
Taste  is  not  a  simple  sense.     Certain  other  sensations,  as 
those  of  touch,  temperature,  smell,  and  pain,  are  blended 

-and  confused  with  it;  and  certain  so-called  tastes  are  really 
sensations  of  another  kind.  Thus  an  astringent  taste,  like 
that  of  alum,  is  more  properly  an  astringent  feeling,  and 

33.  Portions  of  the  tongue  endowed  with  taste?  -  Where  else  does  the  sense 
!od»e  ?  What  is  stated  in  respect  to  sweet  and  bitter  flavors  ?    Reflex  effects  men- 
tioned  ? 

34.  What  is  stated  of  the  relations  of  taste  with  other  senses  ? 


THE   SPECIAL   SENSES.  191 

results  from  an  impression  made  upon  the  nerves  of  touch, 
that  ramify  in  the  tongue.  In  like  manner,  the  qualities 
known  as  smooth,  oily,  watery,  and  mealy  tastes,  are  depend- 
ent upon  these  same  nerves  of  touch.  A  burning  or  pungent 
taste  is  a  sensation  of  pain,  having  its  seat  in  the  tongue  and 
throat.  A  cooling  taste,  like  that  of  mint,  pertains  to  that 
modification  of  touch  called  the  sense  of  temperature. 

35.  Taste  is  largely  dependent  upon  the  sense  of  smell. 
A  considerable  number  of  substances,  like  vanilla,  coffee, 
and  garlic,  which  appear  to  possess  a  strong  and  distinct 
flavor,  have  in  reality  a  powerful  odor,  but  only  a  feeble 
taste.     When  the  sense  of  smell  is  interfered  with  by  hold- 
ing the  nose,  it  becomes  difficult  to  distinguish  between  sub- 
stances of  this  class.    The  same  effect  is  frequently  observed 
when  smell  is  blunted  during  an  ordinary  cold  in  the  head. 
Sight  also  contributes  to  taste.    With  the  eyes  closed,  food 
appears    comparatively    insipid;    and  a   person   smoking 
tobacco  in  the  dark  is  unable  to  determine  by  the  taste 
whether  his  cigar  is  lighted  or  not.     Accordingly,  it  is  not 
a  bad  plan  to  close  the  nose  and  shut  the  eyes  when  about 
to  swallow  some  disagreeable  medicine. 

36.  Influence  of  Education  on  the   Taste.— The 
chief  use  of  the  sense  of  taste  appears  to  be  to  act  as  a 
guide  in  the  selection  of  proper  food.     Hence  its  organs  are 
properly  placed  at  the  entrance  of  the  digestive  canal.     As 
a  general  rule,  those  articles  which  gratify  the  taste  are 
wholesome ;  while  the  opposite  is  true  of  those  which  im- 
press it  disagreeably.      This   statement  is  more  exact  in 
reference  to  the  early  years   of  life   than  to  later  years, 
when,  by  reason  of  mischievous  habits,  the  sense  of  taste 
has  become  dulled  or  perverted.     The  desires  of  a  child 
are  simple ;  he  is  fully  satisfied  with  plain  and  wholesome 
articles  of  diet,  and  must  usually  "learn  to  like"  those 


35.  Its  dependence  on  smell?  on 

36.  The  chief  use  of  the  sense  of  taste?    The  position  of  its  organs  ?    The  rule 
as  regards  wholesome  and  unwholesome  food  ?    Remarks-  respecting  the  rule  ? 


192  THE   SPECIAL   SENSES. 

which  have  a  strongly  marked  flavor.  Accordingly,  it  is 
far  easier  at  this  age  to  encourage  the  preference  for  plain 
food,  and  thus  establish  healthful  habits,  than  later  in  life 
to  uproot  habits  of  indulgence  in  stimulating  substances, 
after  their  ill  effects  begin  to  manifest  themselves. 

37.  The  tastes  of  men  present  the  most  singular  diversi- 
ties, partly  the  result  of  necessity  and  partly  of  habit  or 
education.     The  Esquimaux  like  the  rank  smell  of  whale 
oil,  which  is  a  kind  of  food  admirably  suited  to  the  require- 
ments of  their  icy  climate ;  and  travellers  who  go  from  our 
climate  to  theirs  are  not  slow  to  develop  a  liking  for  the 
same  articles  that  the  natives  themselves  enjoy.    The  sense 
of  taste  is  rendered  very  acute  by  education,  as  is  shown  in 
an  especial   manner    by   those  who   become  professional 
"  tasters"  of  tea  and  wine. 

38.  The   Sense  of  Smell— the  Nasal   Cavities. 
—The  sense   of  smell  is  located  in  the  delicate  mucous 

membrane  which  lines  the  interior  of  the  nose.  That 
prominent  feature  of  the  face,  the  nose,  which  is  merely 
the  front  boundary  of  the  true  nasal  organ,  is  composed 
partly  of  bone  and  partly  of  cartilage.  The  upper  part  of 
it  is  united  with  the  skull  by  means  of  a  few  small  bones ; 
to  which  circumstance  is  due  its  permanence  of  shape. 
The  lower  portion,  or  tip  of  the  nose,  contains  several  thin 
pieces  of  cartilage,  which  render  it  flexible  and  better  able 
to  resist  the  effects  of  blows  and  pressure.  Behind  the 
nose  we  find  quite  a  spacious  chamber,  separated  from 
the  mouth  by  the  hard  palate,  forming  the  "roof  of  the 
mouth,"  and  by  the  soft  palate  (see  Fig.  46) ;  and  divided 
into  two  cavities  by  a  central  partition  running  from  be- 
fore backward. 

39.  These  nasal  cavities,  constituting  the  true  beginning 
of  the  air-passages,  extend  from  the  nose  backward  to  the 

37.  Diversity  in  tastes  of  men  ?    How  shown  ?    The  education  of  the  sense  of 
taste  ? 

38.  Location  of  the  sense  of  smell?    The  nose?    "  Roof  of  the  month?" 

3  J).  Cavities  of  the  nose  ?    Obstruction  of  the  passage  of  air  through  them  ? 


THE   SPECIAL   SENSES. 


193 


upper  opening  of  the  throat,  and  rise  as  high  as  the  junc- 
tion of  the  nose  with  the  forehead.  The  inner  wall  of 
each  cavity  is  straight  and  smooth ;  but  from  the  outer 
wall  there  jut  into  each  cavity  three  small  scroll-like 
bones.  The  structure  of  these  bones  is  very  light,  and 
hence  they  have  been  called  the  "  spongy"  bones  of  the  nose. 
In  this  manner,  while  the  extent  of  surface  is  greatly  in- 
creased by  the  formation  of  these  winding  passages,  the 
cavities  are  rendered  extremely  narrow;  so  much  so,  in  fact, 
that  a  moderate  swelling  of  the  mucous  membrane  which 
lines  them,  as  from  a  cold,  is  sufficient  to  obstruct  the  pass- 
age of  air  through  theni. 

40.  The  Nerve  of  Smell. — The  internal  surface  of 
the  nasal  passages  is  covered  by  a  delicate  and  sensitive 
mucous  membrane.  Its  surface  is  quite  extensive,  follow- 
ing as  it  does,  all  the  inequalities  produced  by  the  curved 
spongy  bones  of  the  nose.  The  upper  portion  of  it  alone 
is  the  seat  of  smell,  since  that  part  alone  receives  branches 
from  the  "first  pair" 
of  cranial  nerves,  or 
the  olfactory  nerve, 
which  is  the  special 
nerve  of  smell  (see 
Fig.  43).  In  Fig.  40 
is  shown  the  distri- 
bution of  this  nerve, 
in  the  form  of  an 
intricate  network 
upon  the  two  upper 

Spongy   bones.      The        FlG'  46--SECTION  OF  THE  RIGHT  NASAL  CAVITY. 

nerve  itself  (1)  does  not  issue  from  the  skull,  but  rests 
upon  a  thin  bone  which  separates  it  from  the  cavity  of  the 
nose;  and  the  branches  which  proceed  from  it  pass  through 
this  bone  by  means  of  numerous  small  openings.  The  en- 


4O.  The  special  nerve  of  smell  ?    Its  location  ? 

9 


THE   SPECIAL   SENSES. 


graving  represents  the  outer  surface  of  the  right  nasal 
cavity;  the  three  wave-like  inequalities,  upon  which  the 
nervous  network  is  spread  out,  are  due  to  the  spongy  bones. 
The  left  cavity  is  supplied  in  the  same  manner. 

41.  The  nerves  which  ramify  over  the  lower  part  of  the 
membrane,  and  which  endow  it  with  sensibility  to  touch 
and  pain,  are  branches  of  the  "  fifth  pair"  of  nerves.     An 
irritation  applied  to  the  parts  where  this  nerve  is  distrib- 
uted occasions  sneezing,  that  is,  a  spasmodic  contraction 
of  the  diaphragm;  the  object  of  which  is  the  expulsion  of 
the  irritating  cause.     The  manner  in  which  the  olfactory 
nerve-fibres  terminate  is  peculiar.     Unlike  the  extremities 
of  other  nerves,  which  are  covered  in  by  a  greater  or  less 
thickness  of  tissue,  these  come  directly  to  the  surface  of 
the  mucous  membrane,  and  thus  come  into  very  close  con- 
tact with  the  odorous  particles  that  are  carried  along  by  the 
respired  air.     The  surface  is  at  all  times  kept  in  a  moist 
condition  by  an  abundant  flow  of  nasal  mucus  ;  otherwise 
it  would  become  dry,  hard,  and  insensitive  from  the  con- 
tinual  passage  of  air  to   and  fro   in  breathing.      Birds, 
which   respire   more   actively  than   men,  have   a  special 
gland,  for  secreting  a  lubricating  fluid,  located  in  the  air- 
passages  of  the  head. 

42.  The  Uses  of  the   Sense  of  Smell,  —  Smell  is 
the  special  sense  which   enables  us  to  appreciate  odors. 
Touch,  as  we  have  seen,  is  largely  concerned  with  solid 
bodies;  and  taste,  with  fluids,  or  with  solids  in  solution. 
Smell,  on  the  other  hand,  is  designed  to  afford  us  informa- 
tion in  reference  to  substances  in  a  volatile  or  gaseous 
form.     Invisible  and  subtile  particles  emanate  from  odor- 
ous bodies,  and  are  brought  by  the  respired  air  in  contact 
with  the  terminal  filaments  of  the  olfactory  nerve,  upon 
which  an  agreeable  or  disagreeable  impression  is  produced. 

4  1  .  Branches  of  the  "  fifth  pair"  of  nerves  ?    Nasal  mucus  ?    Birds  ? 
42.  Smell?    Touch?    Taste?    Design  of  smell  ?    Invisible  and  gaseous  part* 
cles  ?    The  extreme  fineness  of  the  particles  ?    Musk  ?    In  other  cases  ? 


THE   SPECIAL   SENSES.  195 

The  fineness  of  the  particles  that  constitute  odors  is  often  so 
extreme,  that  they  elude  all  attempts  to  measure  or  weigh 
them.  A  piece  of  musk,  for  instance,  may  be  kept  for  sev- 
eral years,  constantly  emitting  perfume,  without  any  ap- 
preciable loss  of  weight.  In  other  cases,  a  loss  of  substance 
is  perceptible,  such  as  the  essential  oils,  which  enter  into 
the  composition  of  the  ordinary  perfumes. 

43.  Smell,  like  taste,  aids  us  in  the  choice  of  proper 
food,  leading  us  to  reject  such  articles  as  have  a  rank  or 
putrid  odor,  and  which  are,  as  a  rule,  unfit  to  be  eaten. 
The  highest  usefulness  of  this  sense,  however,  consists  in 
the  protection  it  affords  to  the  organs  of  respiration.     Sta- 
tioned at  the  gateways  of  the  air-passages,  it  examines  the 
current  of  air  as  it  enters,  and  warns  us  of  the  presence  of 
noxious  gases,  and  of  other  and  generally  invisible  ene- 
mies to  health.     Not  all  dangerous  vapors  are  offensive, 
but  almost  all  offensive  vapors  are  unfit  to  be  breathed.    A 
number  of  small   stiff  hairs  grow   from   the  margin  of 
the  nostrils  to  prevent  the  entrance  of  dust  and  other  at- 
mospheric impurities,  which  would  be  alike  injurious  to  the 
olfactory  mucous  membrane  and  to  the  lungs.    The  benev- 
olent design  of  the  Maker  of  our  bodies  may  be  observed  in 
all  parts  of  their  mechanism ;  but,  probably,  in  none  is  it 
more  clearly  displayed  than  in  connection  with  the  sense 
of  smell. 

44.  The  sense  of  smell  is  developed  in  a  remarkable  de- 
gree in  certain  of  the  inferior  animals,  and  is  especially 
acute  in  reference  to  the  peculiar  emanations  that  appear 
to  characterize  the  different  animals.     The  lion  and  other 
carnivorous  beasts  scent  their  prey  from  a  great  distance; 
and  the  fox-hound  is  able  to  track  the  fox  through  thickets 
and  over  open  country  for  many  miles;  while  the  timid, 
helpless  herbivora,  such  as  the  deer  and  sheep,  find  in  the 


43.  Aid  given  by  ymell?    The  highest  use  of  the  sense?    Explain  the  manner. 

44.  Sense  of  smell  in  the  inferior  animals?     How,  and  in  what  cases,  illus- 
trated ? 


196  THE   SPECIAL   SENSES. 

sense  of  smell  a  means  of  protection  against  their  natural 
enemies,  of  whose  approach  they  are  in  this  manner  warned. 
By  training  this  sense  in  the  dog,  and  making  it  subservi- 
ent to  his  use,  man  is  able  to  hunt  with  success  certain  shy 
and  very  fleet  animals,  which  otherwise  he  could  but  sel- 
dom approach.  Among  men,  individuals  differ  greatly  in 
respect  to  the  development  of  this  sense ;  and  especially 
in  certain  savage  tribes  it  is  found  to  be  extremely  deli- 
cate. Humboldt  states  that  the  natives  of  Peru  can,  by 
this  sense,  distinguish  in  the  dark  between  persons  of  dif- 
ferent races. 

45.  The  Sense  of  Sight. — Sight,  or  Vision,  is  the 
special  sense  by  means  of  which  we  appreciate  the  color, 
form,  size,  distance,  and  other  physical  properties  of  the 
objects  of  external  nature.  Primarily,  this  sense  furnishes 
us  with  information  concerning  the  different  shades  of 
color  and  the  different  degrees  of  tightness:  these  are 
the  simple  sensations  of  sight,  such  as  the  yellowness  and 
glitter  of  a  gold  coin.  In  addition  to  these,  there  are  com- 
posite visual  sensations,  produced  by  the  joint  action  of 
the  other  senses  and  by  the  use  of  the  memory  and  judg- 
ment; such  as,  m  the  case  of  the  coin,  its  roundness, 
solidity,  size,  its  distance  and  direction  from  us.  So  that- 
many  of  our  sensations,  commonly  considered  as  due  to 
sight,  are  in  reality  the  results  of  intellectual  processes 
which  take  place  instantaneously  and  unconsciously. 

•  46.  This  faculty  not  only  has  value  in  the  practical 
every-day  affairs  of  life,  but  it  contributes  so  largely  to  the 
culture  of  the  intellect  and  to  our  higher  forms  of  pleasure, 
that  some  writers  are  disposed  to  rate  it  as  the  first  and 
most  valuable  of  the  senses.  Others,  however,  maintain 
that  the  sense  of  hearing  does  not  yield  in  importance  to 
that  of  sight;  and  they  cite  in  support  of  their  position 

45.  What  is  sight?   What  information  docs  it  furnish  ?    Composite  visual  sen- 
cat  ions  ? 

46.  Comparison  between  sight  and  hearing?    Relative  capacity  of  deaf  and 
blind? 


THE    SPECIAL    SENSES.  19? 


the  fact  that  the  blind  are  commonly  cheerful  and  gay, 
while  the  deaf  are  inclined  to  be  morose  and  melancholy. 
In  respect  to  the  relative  capacity  for  receiving  education 
in  the  deaf  and  blind,  it  is  found  that  the  former  learn 
more  quickly,  but  their  attainments  are  not  profound  ; 
while  the  blind  acquire  more  slowly,  but  are  able  to  study 
more  thoroughly. 

47.  Light. — The  Optic  Nerve. — Unlike  the  senses 
previously  considered — touch,  taste,  and  smell — sight  does 
not  bring  us  into  immediate  contact  with  the  bodies  that 
are  examined;  but,  by  it,  we  perceive  the  existence  and 
qualities  of  objects  that  are  at  a  greater  or  less  distance 
from  us.     In  the  case  of  the  stars,  the  distance  is  incalcu- 
lable, while  the  book  we  read  is  removed  but  a  few  inches. 
Light  is  the  agent  which  gives  to  this  sense  its  wide  range. 
The  nature  of  this  mysterious  force  is  not  known,  and  it  is 
not  here  to  be  discussed;  since  its  study  belongs  more 
properly  to  the  province  of  natural  philosophy. 

48.  It  is  sufficient,  in  this  connection,  to  state  that  the 
theory  of  light  now  generally  accepted,  and  which  best 
explains  the  facts  of  optics,  is  that  known  as  the  undula- 
tory  theory.      This  theory  supposes  that  there  exists  an 
intangible,  elastic  medium,  which  fills  all  space,  and  pene- 
trates all  transparent  substances,  and  which  is  thrown  into 
exceedingly  rapid  undulations  or  waves,  by  the  sun  and 
every  other  luminous  body;  the  undulations  being  propa- 
gated with  extreme  rapidity,  and  moving  not  less  than 
186,000  miles  in  a  second. 

49.  These  waves  are  thought  to  produce  in  the  eye  the 
sensation  of  light,  in  the  same  manner  as  the  sonorous 
vibrations  of  the  air  produce  in  the  ear  the  sensation  of 
sound.     That  part  of  the  eye  which  is  sensitive  to  these 
waves  is  the  expansion  of  the  optic  nerve.     It  is  sensitive 


47.  Sight,  unlike  the  other  senses  ?    In  the  case  of  the  stars  ? 

48.  The  undulatory  theory  oflight?    What  does  the  theory  suppose  ? 

49.  The  sensation  of  light  V    Optic  nerve  ? 


198  THE   SPECIAL   SENSES. 

to  no  other  impression  than  that  of  light,  and  it  is  the  only 
nerve  which  is  acted  upon  by  this  agent.  The  optic  nerve, 
also  called  the  "  second  pair"  of  cranial  nerves,  is  the  means 
of  communication  between  the  eye  and  the  brain. 

50.  The  two   nerves   constituting   the   pair,  arise  from 
ganglia  lying  at  the  base  of  the  cerebrum,  one  of  them  on 
each  side;    from  which  points  they  advance  to  the  eyes, 
being  united  together  in  the  middle  of  their  course  in  the 
form  of  the  letter  X  (Fig.  43 — 2).     By  this  union  the  two 
eyes  are  enabled  to  act  harmoniously,  and  in  some  respects 
to  serve  as  a  double  organ.    And  by  reason  of  this  same  in- 
timate nervous  communication,  when  serious  disease  affects 
one  eye,  the  fellow-eye  is  extremely  liable  to  become  the 
seat  of  sympathetic  inflammation;  and  this,  if  neglected, 
almost  certainly  results  in  hopeless  blindness. 

51.  The  Organ  of  Sight.— The  Eye.— The  proximity 
of  the  eye  to  the  brain,  and  the  important  part  it  per- 
forrfis  in  giving  expression  to  the  emotions,  have  given  it 
the  name  of  "the  window  of  the  soul."     The  exceeding 
beauty  of  its  external  parts,  and  the  high  value  of  its  func- 
tion, have  long  made  this  organ  the  subject  of  enthusiastic 
study.     It  is  chiefly  within  the  last  twenty  years,  however, 
that  this  study  has  been  successful  and  fruitful  of  practical 
results.     Several  ingenious  instruments  have  been  invented 
for  the  examination  of  the  eye  in  health  and  disease,  and 
new  operations  have  been  devised  for  the  relief  of  blindness 
and  of  impaired  vision.     As  a  result,  it  is  now  a  well- 
marked  fact  that,  in  civilized  lands,  the  number  of  those 
who  suffer  from  loss  of  sight  is  proportionally  much  less 
than  in  countries  where  science  is  less  known  and  culti- 
vated. 

52.  The  most  obvious  fact  in  respect  to  the  apparatus  of 


5O»  The  two  nerves  constituting  the  pair  of  nerves  ? 

51.  Why  is  the  eye  called  the  '•  window  of  the  soul?11    Why,  the  subject  of 
enthusiastic  study  ? 

52.  The  most  obvious  fact?    The  consequence?    The  next  thing  noticed? 
Its  range  of  view  ?    Of  what  does  the  organ  of  vision  consist  ? 


THE   SPECIAL   SENSES.  199 

sight  is  that  there  are  two  eyes,  which  may  either  act  to- 
gether as  one,  and  be  fixed  upon  one  object,  or  one  eye  may 
be  used  independently  of  the  other.  In  consequence  of 
this  arrangement  the  loss  of  one  eye  does  not  necessitate 
blindness,  and,  in  fact,  it  not  infrequently  happens  that  the 
sight  of  one  eye  may  be  long  impaired  or  lost  before  the 
fact  is  discovered.  We  next  notice  that  it  is  placed  at  the 
most  elevated  part  of  the  body,  in  front,  and  near  the  brain. 
It  also  commands  a  wide  range  of  view,  being  itself  moved 
with  great  rapidity,  and  being  further  aided  by  the  free 
motion  of  the  head  and  neck.  The  organ  of  vision  consists 
essentially  of  two  parts  :  the  optical  instrument  itself — the 
eyeball — and  its  enveloping  parts,  or  the  case  in  which  the 
instrument  is  kept  free  from  harm.  The  latter,  which  are 
external,  and  which  we  shall  first  consider,  are  chiefly  the 
Orbits,  the  Eyelids,  and  the  apparatus  for  the  Tears. 

53.  The  Orbits. — The  eyeball,  which  is  a  delicate 
organ,  is  well  defended  against  external  injury  within  the 
orbits  or  bony  sockets  of  the  head.  These  are  deep  conical 
hollows,  bounded  in  part  by  the  bones  of  the  skull,  and  in 
part  by  those  of  the  nose  and  cheek.  The  orbit  juts  out 
beyond  the  most  exposed  portion  of  the  eyeball,  as  may  be 
seen  by  laying  a  book  over  the  eye,  when  it  will  be  found 
that  no  part  of  the  eyeball,  unless  it  be  very  prominent, 
will  be  touched  by  the  book ;  so  that  the  only  direction  in 
which  an  injury  is  liable  to  be  received  is  immediately  in 
front  of  the  eye.  The  overhanging  brow  is  itself  covered 
by  a  layer  of  thick  skin,  studded  with  short,  stout  hairs, 
which  are  so  bent  as  to  prevent  the  perspiration  from  run- 
ning into  the  eye  and  obscuring  vision.  Through  a  hole 
in  the  bottom  of  the  orbit,  the  nerve  of  sight  passes  out- 
ward from  the  brain.  The  orbit  also  contains  a  considera- 
ale  amount  of  a  fatty  tissue,  upon  which,  as  upon  an  elastic 
cushion,  the  eye  rests. 

53.  The  protection  of  the  eyeball  against  injury?     The  overhanging  brow? 
The  opening  for  the  optic  nerve  ? 


200 


THE   SPECIAL   SENSES. 


FIG.  47.— FRONT  VIEW  op  RIGHT  EYE. 
(Natural  Size.) 

1.  The  Lachrymal,  or  tear  gland,  lying  be- 
neath the  upper  eyelid. 

2.  The  Nasal  Duct  is  shown  by  the  dotted 
line.    The  *  marks  the  orifice  iu  the  lower 
lid. 

The  central  black  spot  is  the  pupil;  sur- 
rounding it  is  the  iris ;  and  the  triangular 
white  spaces  are  the  visible  portion  of  the 
sclerotic. 


54.  The  Eyelids. — The  eyelids  are  two  movable  cur- 
tains, or  folds,  which,  when  shut,  cover  the  front  part  of 

the  orbit,  and  hide  the 
eye  from  view.  The  up- 
per lid  is  the  larger,  has  a 
curved  margin,  and  moves 
freety,  while  the  lower  lid 
is  comparatively  short 
and  straight,  and  has  but 
a  slight  degree  of  motion 
(Fig.  47).  Skin  covers 
the  exterior  of  the  lids, 
while  a  fine  mucous 
membrane  lines  their  in- 
ner surface,  and  is  like- 
wise spread  out  over  the 
entire  front  of  the  eye- 
ball. This  membrane, 
which  is  called  the  Conjunctiva,  is  highly  sensitive,  and 
thus  plays  an  important  part  in  protecting  the  eye  against 
the  lodgment  of  sand,  ashes,  chaff,  and  other  foreign  parti- 
cles that  are  blown  about  in  the  air.  This  sensitive  mem- 
brane will  not  endure  the  presence  of  these  particles.  If 
any  find  access,  it  causes  a  constant  winking,  a  flow  of 
tears,  and  other  signs  of  irritation,  until  it  is  removed. 

55.  The  long,  silky  eyelashes,  which  garnish  the  edges 
of  the  lids,  act  like  a  sieve  to  prevent  the  entry  of  dust  and 
the  like;   and  together  with   the  lids,  they  regulate  the 
amount  of  light  which  is  permitted  to  enter  the  eye,  so  that 
it  is  shielded  from  a  sudden  flood  or  glare  of  light.  The  little 
points  seen  in  the  figure  just  within  the  line  of  the  lashes, 
especially  on  the  lower  lid,  represent  the  months  of  numer- 
ous little  sebaceous  glands  (Fig.  48,  D,D),  such  as  are  always 

54.  What  are  the  eyelids?    The  upper  lid?     The  lower  one?    The  mucous 
membrane  of  the  eye  ? 

55.  The  eyelashes?    The  little  points  within  the  line  of  the  lashes  ?    Of  what 
use  are  these  glands  ? 


THE   SPECIAL   SENSES.  201 

found  in  the  neighborhood  of  hairs.  These  glands  supply 
a  thick,  oily  material  which  greases  the  edges  of  the  lids 
and  prevents  their  adhering  together,  and  likewise  prevents 
the  overflow  of  the  tears  upon  the  cheek. 

56.  The  Lachrymal  Fluid,  or  the  Tears. — Just 
within  the  outer  part  of  the  bony  arch  cf  the  brow,  where 
the  bone  may  be  felt  to  be  sharper  than  in  other  positions, 
is  lodged  a  little  organ  called  the  lachrymal  gland,  the  sit- 
uation of  which  is  indicated  in  Fig.  47,  1.     This  is  the 
gland  whence  flows  the  watery  secretion,  commonly  called 
the  tears,  which  is  designed  to  perform  an  exceedingly  im- 
portant duty  in  lubricating  the  lids,  and  in  keeping  the 
exposed  surface  of  the  eyeball  moist  and  transparent.    For, 
without  this  or  some  similar  liquid,  the  front  of  the  eye 
would  speedily  become  dry  and  lustreless,  like  that  of  a 
fish  which  has  been  removed  from  the  water :  the  simple 
exposure  of  the  eye  to  the  air  would  then  suffice  to  destroy 
vision. 

57.  This  secretion  of  the  tears  takes  place  at  all  times, 
during  the  night  as  well  as  the  day;   but  it  is  seldom 
noticed,  except  when  under  the  influence  of  some  strong 
mental   emotion,  whether  of  sorrow  or   happiness,  it   is 
poured  forth  in  excess,  so  as  to  overflow  the  lids.     Strong 
light  or  a  rapid  breeze  will,  among  many  other  causes,  ex- 
cite the  flow  of  the  tears.     That  portion  of  this  secretion 
which  is  not  used  in  moistening  the  eye   is  carried  off 
into  the  nose  by  a  canal  situated  near  the  inner  angle  of 
the  eye,  called  the  nasal  duct.     This  duct  is  shown  in  Fig. 
47,  2,  and  is  connected  with  each  lid  by  delicate  tubes, 
which  are  indicated  by  dotted  lines  in  the  figure ;  the  as- 
terisk marks  the  little  opening  in  the  lower  lid,  by  which 
the  tears  enter  the  nasal  duct.     By  gently  turning  the 
inner  part  of  that  lid  downward,  and  looking  in  a  mirror, 

56.  The  location  of  the  lachrymal  gland  ?    The  use  of  the  gland  ? 

57.  When  does  the  secretion  of  the  tears  occur?    The  secretion  not  used  for 
the  eye?    Location  of  the  nasal  duct?    Its  use?    The  overflow  of  tears  in  old 
people  ? 

9* 


202 


THE   SPECIAL   SENSES. 


this  small  "lachrymal  point''  may  be  seen  in  your  own 
eye.  In  old  people,  these  points  become  everted,  and  do 
not  conduct  the  tears  to  the  nasal  cavity,  so  that  they  are 
inconvenienced  by  an  overflow  of  tears  upon  the  face. 

58.  Thus  we  observe  that  the  gland  which  forms  the 
tears  is  placed  rt  the  outer  part  of  the  eye,  while  their 
means  of  exit  is  at  the  inner  angle  of  the  eye;  which  fact 
renders  it  necessary  that  this  watery  fluid  shall  pass  over 
the  surface  of  the  eyeball  before  it  can  escape.  This  ar- 


FIG.  48.— VERTICAL  SECTION  OF  THE  EYE.     (Enlarged.) 


C,  The  Cornea. 

A,  The  Aqueous  Humor. 
I.  The  Iris*. 

P,  The  Pupil. 

L,  The  Crystalline  Lens.    ' 

H,  The  Ligament  of  the  Lens. 

B,  The  Ciliary  Process. 

V,  The  Cavity  containing  the  Vit- 
reous Humor. 
S,  The  Sclerotic. 


Ch,  The  Choroicl. 

R,  The  Retina. 

N.  The  Optic  Nerve. 

DD.  The  Eyelids. 

X,  The  Levator  Muscle  of  the  Upper 

Lid. 
Y,  The  Upper  Straight  Muscle  of  the 

Eye. 
Z,  The  Lower  Straight  Muscle. 


rangement  cannot  be  accidental,  but  evinces  design,  for  it 
thus  secures  the  perfect  lubrication  of  the  surface  of  the 
eve,  and  cleanses  it  from  the  smaller  particles  of  dust 


58.  The  watery  fluid  passing  over  the  eyeball  ?    Design  of  the  arrangement  ? 
Winking  ? 


THE   SPECIAL   SENSES.  203 


which  may  enter  it,  in  spite  of  the  vigilance  of  the  lids 
and  lashes.  The  act  of  winking,  which  is  generally  un- 
consciously performed,  and  which  takes  place  six  or  more 
times  in  a  minute,  assists  this  passage  of  the  tears  across 
the  eye,  and  is  especially  frequent  when  the  secretion  is 
most  abundant. 

59.  The   Eyeball. — The  remarkable    optical   instru- 
ment called  the  eyeball,  or  the  globe  of  the  eye,  upon 
which  sight  depends,  is,  as  the  name  indicates,  spherical  in 
shape.     It  is  not  a  perfect  sphere,  since  the  front  part  pro- 
jects somewhat  beyond  the  rest,  and  at  the  posterior  part 
the  optic  nerve  (Fig.  48,  N)  is  united  to  it,  resembling  the 
junction  of  the  stem  with  a  fruit.     In  its  long  diameter, 
that  is,  the  horizontal  or  from  side  to  side,  it  measures  a 
little  more  than  an  inch;  in  other  directions  it  is  rather 
less  than  an  inch.    In  structure,  the  ball  of  the  eye  is  firm, 
and  its  tense  round  contour  may  in  part  be  felt  by  pressing 
the  fingers  over  the  closed  lids. 

60.  The  eyeball  is  composed  chiefly  of  three   internal, 
transparent   media,  called  humors;   and  three   investing 
coats,  or  tunics.     The  former  are  the  aqueous  humor,  Fig. 
48,   A,  the  crystalline  lens  L,  and  the  vitreous  humor  v. 
Of  these  the  lens  alone  is  solid.     The  three  coats  of  the 
eyeball  are  called  the  sclerotic  s,  the  choroid  CH,  and  the 
retina  R.     This  arrangement  exists  in  respect  to  five-sixths 
of  the  globe  of  the  eye,  but  in  the  anterior  one-sixth,  these 
coats  are  replaced  by  the  cornea  c,  which  is  thin  and  trans- 
parent, so  that  the  rays  of  light  pass  freely  through  it,  as 
through  a  clear  window-pane. 

61.  In   shape,   the  cornea  is  circular  and  prominent, 
resembling  a  miniature  watch-glass,  about  -fa  of  an  inch 
thick.     In  structure,  it  resembles  horn  (as  the  name  signi- 
fies), or  the  nail  of  the  finger,  and  is  destitute  of  blood- 


59.  Describe  the  shape  of  the  eyeball.     Its  structure. 

GO.  Of  what  is  the  eyeball  composed  *     State  how. 

6 1 .  The  shape  of  the  cornea  ?    Its  structure  ?    The  "  white  of  the  eye  ?' 


204  THE   SPECIAL   SENSES. 

vessels.  The  Sclerotic  (from  scleros,  hard)  is  composed  of 
dense,  white  fibrous  tissue,  and  gives  to  the  eyeball  its 
firmness  of  figure  and  its  white  color.;  in  front,  it  consti- 
tutes the  part  commonly  called  "the  white  of  the  eye." 
It  is  one  of  the  strongest  tissues  in  the  body ;  it  possesses 
very  few  vessels,  and  is  not  very  sensitive.  It  affords  pro- 
tection to  the  extremely  delicate  interior  parts  of  the  eye; 
and  the  little  muscles  which  effect  its  movements  are  in- 
serted into  the  sclerotic  a  short  distance  behind  the  cornea 
(see  Fig.  48,  Y,  z).  It  is  perforated  posteriorly  to  admit  the 
optic  nerve. 

62.  The  Choroid  is  the  second  or  middle  coat  of  the  eye- 
ball, and  lies  closely  attached  to  the  inner  surface  of  the 
sclerotic.     Unlike  the  latter  tunic,  its  structure  is  soft  and 
tender,  it  is  dark  in  color,  and  possesses  a  great  abundance 
of  blood-vessels.     Its  dark  color  is  due  to  a  layer  of  dark 
brown  or  chocolate-colored  cells  spread  out  over  its  inner 
surface.     This  dark  layer  serves  to  absorb  the  rays  of  light 
after  they  have  traversed  the  transparent   structures  in 
front  of  it ;  if  the  rays  were  reflected  from  side  to  side 
within  the  eye,  instead  of  being  thus  absorbed,  confused 
vision  would  result  from   the  multitude  of  images  which 
would  be  impressed  upon  the  optic  nerve. 

63.  This  mechanism  has  been  unconsciously  imitated  by 
the  opticians,  who,  when  they  make  a  microscope  or  tele- 
scope, take  care  that  the  interior  of  its  tube  shall  be  coated 
with  a  thick  layer  of  black  paint  or  lamp-black;  for  with- 
out it,  a  clear  delineation  of  the  object  to  be  viewed  is  im- 
possible.    The  albinos,  in  whom  these  dark  cells  of  the 
choroid  are  wanting,  have  imperfect  vision,  especially  in 
the  daytime  and  in  strong  lights.     The  dark  cells  are  also 
wanting  in  white  rabbits,  and  other  animals  that  have  red 
or  pink  eyes ;  their  vision  appears  to  be  imperfect  in  the 
presence  of  a  bright  light. 

62.  The  second  or  middle  coat  of  the  eyeball  ?    Its  dark  color  ? 

63.  Similar  mechanism  in  microscopes  ?    The  albinos  ?    White  rabbits? 


THE   SPECIAL  SENSES.  205 

64.  The  Iris. — Continuous  with  the  choroid,  in  the  front 
part  of  the  globe  of  the  eye,  is  a  thin,  circular  curtain, 
which  occasions  the  brown,  blue,  or  gray  color  of  the  eye 
in  different  individuals.     On  account  of  the  varieties  of  its 
color,  this  membrane  has  received  the  name  Iris,  which  is 
the  Greek  word  for  "rainbow"  (see  Fig.  48,  i).    A  front 
view  of  it  is  shown  in  Fig.  47.    The  iris  is  pierced  in  its 
centre  by  a  round  opening,  called  the  pupil  (P),  which  is 
constantly  varying  in  size.     In  olden  times  it  was  spoken 
of  as  the  "  apple  of  the  eye."     The  hinder  surface  of  the 
iris,  except  in  albinos,  has  a  layer  of  dark  coloring  matter 
resembling  that  of  the  choroid.     The  iris  is  a  muscular 
organ,  and  contains  two  distinct  sets  of  fibres;  one  of  which 
is  circular,  while  the  other  radiates  outward  from  the  pupil. 
The  action  of  these  sets  of  fibres  regulates  the  size  of  the 
pupil ;  for  when  the  circular  set  acts,  the  pupil  contracts, 
and  when  the  other  set  acts,  the  opening  expands.     Their 
action  is  involuntary,  and  depends  on  the  reflex  system  of 
nerves,  which  causes  the  contraction  of  the  pupil  when  a 
strong  light  falls  upon  the  eye,  and  its  expansion  when 
the  illumination  is  feeble. 

65.  The  iris,  accordingly,  serves  a  very  useful  purpose 
in  regulating  the  admission  of  light  to  the  eye.     It,  how- 
ever, does  not  act  instantaneously;  and  hence,  when  we 
pass  quickly  from  a  dark  room  into  the  bright  sunlight, 
the  vision  is  at  first  confused  by  the  glare  of  light,  but  as 
soon  as  the  pupil  contracts,  the  ability  to  see  becomes  per- 
fect.    On  the  other  hand,  when  we  enter  a  dark  apart- 
ment, such  as  a  cellar,  for  a  short  time  we  can  see  nothing 
clearly ;  but  as  soon  as  the  pupil  expands  and  admits  more 
light,  we  are  enabled  to  distinguish  the  surrounding  ob- 
jects.    Animals  of  the  cat  species,  and  others  which  prowl 
around  after  nightfall,  are  enabled  to  see  in  the  dark  by 

64.  What  is  the  iris  ?    Its  construction  ?    How  is  the  size  of  the  pupil  regu- 
lated ? 

65.  The  admission  of  light  to  the  eye  ?    The  action  of  the  iris  under  different 
circumstances'?    The  lustre  of  the  eye,  how  affected  in  youth  and  old  age  ? 


206  THE   SPECIAL   SENSES. 

having  the  iris  very  dilatable.  The  size  of  the  pupil  affects 
the  lustre  of  the  eye.  When  it  is  large,  as  it  usually  is  dur- 
ing youth,  the  eye  appears  clear  and  brilliant;  while  in  old 
age  the  pupil  is  small  and  the  eye, is  dull.  The  brilliancy 
of  the  eye  is  in  part,  at  least,  dependent  upon  the  reflec- 
tion of  light  from  the  front  surface  of  the  crystalline  lens. 

66.  Certain  poisonous  vegetables  have  the  property  of 
causing  the  pupil  to  dilate,  and  have  been  used  in  small 
doses  to  increase  the  beauty  of  the  eye.  One  of  these 
drugs  has  been  so  largely  used  by  the  ladies  for  this  pur- 
pose, that  it  has  received  the  name  belladonna,  from  the 
Italian  words  meaning  "  beautiful  lady."  This  hazardous 
practice  has  resulted  more  than  once  in  the  death  of  the 
person  desiring  thus  to  increase  her  personal  attraction. 
The  common  English  name  for  belladonna  is  "deadly 
nightshade."  (In  the  diagram  on  page  214  the  shape  and 
relations  of  the  iris  are  more  accurately  shown  than  in  the 
figure  referred  to  above.) 

67-  The  Retina  constitutes  the  third  and  inner  coat  of 
the  globe  of  the  eye.  This,  the  important  part  of  the  eye 
that  is  sensitive  to  light,  is  a  kind  of  nervous  membrane, 
formed  by  the  expansion  of  the  ultimate  filaments  of  the 
optic  nerve.  Its  texture  is  soft,  smooth,  and  very  thin; 
it  is  translucent  and  of  an  opaline,  or  grayish-white 
color.  It  is  sensitive  to  light  alone ;  and  if  any  form  of 
mechanical  irritation  be  applied  to  it,  the  sensations  of 
touch  and  pain  are  not  experienced,  but  flashes  of  fire, 
sparks,  and  other  luminous  appearances  are  perceived. 
Thus  an  electric  shock  given  to  the  eye-ball  occasions  a 
flash  of  light ;  and  a  sudden  fall,  or  a  blow  upon  the  eye, 
is  often  apparently  accompanied  by  the  vision  of  "stars." 

68.  These   phenomena  are  due  to  what  is  termed  the 


66.  Means  used  to  increase  the  beauty  of  the  eye  ?     The  injurious  conse- 
quences * 

67.  What  part  does  the  retina  constitute  ?    How  formed?    Its  texture  ?   Color? 
Sent"  itiveness  ? 

68.  Specific  energy  of  the  optic  nerve  ?    Trial  in  Germany  ? 


THE   SPECIAL   SENSES.  207 

"  specific  energy"  of  the  optic  nerve,  which  nerve,  in  com- 
mon with  the  other  nerves  of  special  sense,  obeys  a  general 
law  of  nature,  which  requires  that,  whenever  one  of  these 
nerves  is  stimulated,  it  shall  respond  with  the  sensation 
peculiar  to  itself.  These  flashes  of  retinal  light  have  no 
power  to  illuminate  external  objects,  although  the  opposite 
of  this  statement  has  been  maintained.  On  the  occasion 
of  a  remarkable  trial  in  Germany,  it  was  claimed  by  a  per- 
son who  had  been  severely  assaulted  on  a  very  dark  night, 
that  the  flashes  of  light  caused  by  repeated  blows  upon  the 
head  enabled  him  to  see  with  sufficient  distinctness  to 
recognize  his  assailant.  But  the  evidence  of  scientific 
men  entirely  refuted  this  claim,  by  pronouncing  that  the 
eye,  under  the  circumstances  named,  was  incapacitated  foi 
vision.  Too  intense  light  occasions  a  feeling  of  pain,  but 
it  is  of  a  peculiar  kind,  and  is  termed  "dazzling." 

69.  All  parts  of  the  retina  are  not  equally  sensitive,  and 
singularly  enough,  the  point  of  entry  of  the  nerve  of  sight, 
in  the  back  part  of  the  eyeball,  is  entirely  insensible  to  light, 
and  is  called  the  "blind  spot."  The  existence  of  this  point 
may  be  proven  by  a  simple  experiment.  Hold  the  accom- 


FIG.  49. 

panying  figure,  on  page  207,  directly  in  front  of  and  paral- 
lel with  the  eyes.  Close  the  left  eye,  and  fix  the,  sight 
steadily  on  the  left-hand  circle ;  then,  by  gradually  varying 
the  distance  of  the  figure  from  the  eye,  at  a  certain  dis- 
tance (about  six  inches),  the  right-hand  circle  will  disappear, 

69.  Sensitiveness  of  all  parts  of  the  retina  ?    Experiment  to  prove  the  exist- 
ence of  the  "blind  spot.1' 


208  THE   SPECIAL   SENSES. 

but  nearer  or  further  than  that,  it  will  be  plainly  seen. 
The  other  eye  may  be  also  tried,  with  a  similar  result :  if 
the  gaze  be  directed  to  the  right-hand  circle,  the  left  one 
will  seem  to  disappear.  The  experiment  may  be  repeated 
by  using  two  black  buttons  on  the  marble  top  of  a  bureau, 
or  on  some  other  white  surface.  The  blind  spot  does  not 
practically  interfere  with  vision,  since  the  eye  is  seldom 
fixed  immovably  on  an  object,  and  the  insensitive  parts  of 
the  two  eyes  can  never  be  directed  upon  the  same  object  at 
the  same  time. 

70.  Impressions  made  upon  the  retina  are  not  at  once 
lost,  but  persist  a  measurable  length  of  time,  and  then 
gradually  fade  away.     Thus,  a  bright  light  or  color,  gazed 
at  intently,  cannot  be  immediately  dismissed  from  sight  by 
closing  or  turning  away  the  eyes.     A  stick  lighted  at  one 
end,  if  whirled  around  rapidly  in  the  dark,  presents  the 
appearance  of  an  unbroken  luminous  ring;  and  the  spokes 
of  a  rapidly  revolving  carriage-wheel  seem  to  be  merged 
into  a  plane  surface.    If  an  object  move  too  rapidly  to  pro- 
duce this  sort  of  lasting  impression,  it  is  invisible,  as  in1  the 
case  of  a  cannon-ball  passing  through  the  air  in  front  of 
us. 

71.  If  a  card,  painted  with  two  primary  colors— as  red  and 
yellow — be  made  to  rotate  swiftly,  the  eye  perceives  neither 
of  them  distinctly  ;  but  the  card  appears  painted  with  their 
secondary -color — orange.     The  average  duration  of  retinal 
images  is  estimated  at  one-eighth  of  a  second ;  and  it  is 
because  ihey  thus  endure,  that  the  act  of  winking,  which 
takes  place  so  frequently,  but  so  quickly,  is  not  noticed  and 
does  not  interrupt  the  vision.     The  retina  is  easily  fatigued 
or  deprived  of  its  sensibility.     After  looking  steadfastly  at 
a  bright  light,  or  at  a  white  object  on  a  black  ground,  a 
dark  spot,  corresponding  in  shape  to  the  bright  object, 


70.  Duration  of  impressions  upon  the  retina  ?    How  illustrated  ? 

71.  What  further  illustration?    Winking,  why  it  is  not  noticed.     Ease  wit' 
which  the  retina  is  fatigued  or  deprived  of  sensibility  ?    How  shown  ? 


THE   SPECIAL   SENSES.  209 

presents  itself  in  whatever  direction  we  look.     This  spot 
passes  away  as  the  retina  resumes  its  activity. 

72.  If  a  bright  color  be  gazed  at  intently,  and  the  eyes 
then  be  turned  to  a  white  surface,  a  spot  will  appear ;  but 
its  color  will  be  the  complement  of  that  of  the  object.     Fix 
the  eye  upon  a  red  wafer  upon  a  white  ground,  and  on  re- 
moving the  wafer  a  greenish  spot  of  the  same  shape  takes 
its  place.    This  result  happens  because  a  certain  portion  of 
the  retina  has  exhausted  its  power  to  perceive  the  red  ray, 
and  perceives  only  its  complementary  ray,  which  is  green. 
The  color  thus  substituted  by  the  exhausted  retina  is  called 
a  physiological  or  accidental  color.     In  some  persons  the 
retina  is  incapable  of  distinguishing  different  colors,  when 
they  are  said  to  be  affected  with  "  color-blindness."     Thus, 
red  and  green  may  appear  alike,  and  then  a  cherry-tree, 
full  of  ripe  fruit,  will  seem'bf  the  same  color  in  every  part. 
Railroad  accidents  have  occurred  because  the  engineer  of 
the  train,  who  was  color-blind,  has  mistaken  the  color  of  a 
signal. 

73.  The  Crystalline  Lens.— Across  the  front  of  the 
eye,  just  behind  the  iris,  is  situated  the  Crystalline  lens, 
enclosed  within  its  own  capsule.     It  is  supported  in  its 
place  partly  by  a  delicate  circular  ligament,  and  partly  by 
the  pressure  of  adjacent  structures.     It  is. colorless  and  per- 
fectly transparent,  and  has  a  firm  but  elastic  texture.     In 
shape  it  is  doubly  convex,  and  may  be  rudely  compared  to 
a  small  lemon-drop.     The  front  face  of  the  lens  is  flatter 
than  the  other,  and  is  in  contact  with   the  iris^near   its 
pupillary  margin,  as  is  represented  in  the  diagram  on  page 
214.     It  is  only  one-fourth  of  an  inch  thick. 

74.  When  this  little  body  becomes  opaque,  and  no  longer 
affords  free  passage  to  the  rays  of  light,  as  often  happens 

72.  How  further  shown?     How  is  the  result  accounted  for?    " Color-blind- 
ues»B  ?" 

73.  The  location  of  the  crystalline  lens?     How  supported?     Its  color  and 
texture?    Shape?    Size? 

Y4.  Cataract?    Aqueous  humor ?    Vitreous  humor ? 


210  THE  SPECIAL   SENSES. 

with  the  advance  of  age,  an  affection  termed  "  cataract"  is 
produced.  Between  the  crystalline  lens  and  the  cornea  is 
a  small  space  which  contains  the  aqueous  humor  (see  Fig. 
48,  A).  This  humor  consists  of  five  or  six  drops  of  a  clear, 
colorless  liquid  very  much  like  water,  as  its  name  implies. 
That  part  of  the  globe  of  the  eye  lying  behind  the  lens  is 
occupied  by  the  vitreous  humor,  so  called  from  its  fancied 
resemblance  to  melted  glass  (Fig.  48,  v).  This  humor  is  a 
transparent,  jelly-like  mass,  enclosed  within  an  exceed- 
ingly thin  membrane.  It  lies  very  closely  applied  to  the 
retina,  or  nervous  membrane  of  the  eye,  and  constitutes 
fully  two-thirds  of  the  bulk  of  the  eyeball. 

75.  The  Uses  of  the  Crystalline  Lens. — A  con- 
vex lens  has  the  property  of  converging  the  rays  of  light 
which  pass  through  it ;  and  the  point  at  which  it  causes 


FIG.  50.— THE  RETINAL  IMAGE. 

them  to  meet  is  termed  its  focus.  If  a  lens  of  this  descrip- 
tion, such  as  a  magnifying  or  burning-glass,  be  held  in 
front  of  an  open  window,  in  such  a  position  as  to  allow 
its  focus  to  fall  upon  a  piece  of  paper,  it  will  be  found  to 
depict  upon  the  paper  a  miniature  image  of  the  scene  out- 
side of  the  window.  It  will  be  further  noticed  that  the 
image  is  inverted,  or  upside  down,  and  that  the  paper 


75.  What  is  a  lens  and  its  focus  ?    The  miniature  image,  how  produced  T 


THE   SPECIAL  SENSES. 


at  the  place  upon   which  the  image  is  thrown  is  much 
brighter  than  any  other  part. 

76.  Now  all  the  transparent  structures  of  the  eye,  but 
especially  the  crystalline  lens,  operate  upon  its  posterior 
part,  or  retina,  as  the  convex  lens  acts  upon  the  paper  ;  that 
is,  they  paint  upon  the  retina  a  bright  inverted  miniature 
of  the  objects  that  appear  in  front  of  the  eye  (Fig.  50). 
That  this  actually  takes  place  may  be  proved  by  experi- 
ment.    If  the  eyeball  of  a  white  rabbit,  the  walls  of  which 
are  transparent,  be  examined  while  a  lighted  candle  is  held 
before  the  cornea,  an  image  of  the  candle-flame  may  be 
seen  upon  the  retina. 

77.  The  form  and  structure  of  the  crystalline  lens  endow 
it  with  a  remarkable  degree  of  refractive  power,  and  en- 
able  it   to   converge   all   the  rays  of  light  that  enter  it 
through  the  pupil,  to  a  focus  exactly  at  the  surface  of  the 
retina.     When  this  lens  is  removed  from  the  eye,  as  is 
frequently  done  for  the  cure  of  cataract,  it  is  found  that 
the  rays  of  light  then  have  their  focus  three-eighths  of  an 
inch  behind  the  retina;  that  the  image  is  four  times  larger 
than  in  the  healthy  eye,  that  it  is  less  brilliant,  and  that 
its  outline  is  very  indistinct.     From  this  we  learn  that  one 
of  the  uses  of  the  crystalline  lens  is  to  make  the  retinal 
image  bright  and  sharply-defined,  at  the  same  time  that  it 
reduces  its  size.     Indeed,  the  small  size  of  the  image  is  a 
great  advantage,  as  it  enables  the  limited  surface  of  the 
retina  to  receive,  at  a  glance,  impressions  from  a  consider- 
able field  of  vision. 

78.  As  the  image  upon  the  retina  is  inverted,  how  does 
the  mind  perceive  the  object  in  its  true,  erect  position  ? 
Many  explanations  have  been  advanced,  but  the  simplest 
and  most  satisfactory  appears  to  be  found  in  the  fact  that 


76.  How  are  figures  painted  upon  the  retina  ?    How  proved  ? 

77.  What  can  be  said  in  respect  to  the  form  and  structure  of  the  crystalline 
lens? 

78.  How  is  the  inverted  image  upon  the  retina  presented  in  its  true  position  to 
the  mind? 


212  THE   SPECIAL   SENSES. 


the  retina  observes  no  difference,  so  to  speak,  between  the 
right  and  left  or  the  upper  and  lower  positions  of  objects. 
In  fact,  the  mind  is  never  conscious  of  the  formation  of  a 
retinal  image,  and  until  instructed,  has  no  knowledge  that 
it  exists.  Consequently,  our  knowledge  of  .the  relative 
location  of  external  objects  must  be  obtained  from  some 
other  source  than  the  retina.  The  probable  source  of  this 
knowledge  is  the  habitual  comparison  of  those  objects  with 
the  position  of  our  own  bodies:  thus,  to  see  an  elevated 
object,  we  know  we  must  raise  the  head  and  eyes ;  and  to 
see  one  at  our  right  hand,  we  must  turn  the  head  and  eyes 
to  the  right. 

79.  Long-sight  or  Hyperopia,  and  Short-sight 
or  Myopia. — The  eye  is  not  in  all  cases  perfectly 
formed.  For  example,  persons  may  from  birth  have  the 
cornea  too  prominent  or  too  flat,  or  the  lens  may  be  too 
thick  or  too  thin.  In  either  of  these  conditions  sight  will 


Fro.  51.— THE  DIFFERENT  SHAPES  OF  THE  GLOBE  OF  THE  EYE. 

N,  The  Natural  Eye.  M,  The  Short-sighted  Eye. 

H,  The  Long-sighted  Eye.  S,  Parallel  Rays  from  the  Sun. 

be  more  or  less  defective  from  the  first,  and  the  defect  will 
not  tend  to  disappear  as  life  advances.  The  most  common 
imperfection,  however,  is  in  the  shape  of  the  globe ;  which 
may  be  short  (Fig.  51,  H),  as  compared  with  the  natural 
eye,  N,  or  it  may  be  too  long,  M. 

80.  When  the  globe  is  short,  objects  can  only  be  clearly 

79.  The  uniform  perfection  of  the  eye?    Examples?    The  most  common  im- 
perfection ? 

80.  How  is  "  long-sight"1  explained?    "Short-sight?" 


THE   SPECIAL   SENSES.  213 


seen  that  are  at  a  distance,  and  the  condition  of  the  vision 
is  known  as  "long-sight,"  or  hyperopia.  It  will  be  ob- 
served, by  reference  to  Fig.  51,  that  the  focus  of  the 
rays  of  light  would  fall  behind  the  retina  of  this  eye. 
When  the  globe  is  too  long,  objects  can  only  be  clearly  seen 
that  are  very  near  to  the  eye;  and  the  condition  resulting 
from  this  defect  is  termed  "  short-sight,"  or  myopia.  The 
focus  of  the  rays  of  light  is,  in  this  case,  formed  in  the 
interior  of  the  eye  in  front  of  the  retina. 

81.  Long-sight,  or  hyperopia,  is  common  among  school- 
children, nearly  as  much  so  as  short-sight,  and  must  not  be 
confounded  with  the  defect  known  as  the  "  far  sight"  of 
old  people;  although  in  both  affections  the  sight  is  im- 
proved by  the  use  of  convex  glasses.     Children  not  infre- 
quently discover   that   they  see   much  better  when  they 
chance  to  put  on  the  spectacles  of  old  persons.     For  the 
relief  of  short-sight,  concave  glasses  should  be  employed; 
as  they  so  scatter  the  rays  of  light  as  to  bring  the  focus  to 
the  retina,  and   thus  cause  the  vision  of  remote  objects 
to  become  at  once  distinct.     That  form  of  "squint,"  in 
which  the  eyes  are  turned  inward,  is  generally  dependent 
upon  long-sight,  while  that  rarer  form,  when   they  turn 
outward,  is  due  to  short-sight. 

82.  The  Function  of  Accommodation. — If,  after 
looking  through  an  opera-glass  at  a  very  distant  object,  it 
is  desired  to  view"  another  nearer  at  hand,  it  will  be  found 
impossible  to  obtain  a  clear  vision  of  the  second  object  un- 
less the  adjustment  of  the  instrument  is  altered ;  which  is 
effected  by  means  of  the  screw.    If  an  object,  like  the  end  of 
a  pencil,  be  held  near  the  eye,  in  a  line  with  another  object 
at  the  other  side  of  the  room,  or  out  of  the  window,  and 
the  eye  be  fixed  first  apon  one  and  then  upon  the  other,  it 
will  be  found  that  when  the  pencil  is  clearly  seen,  the  fur- 
si.  Lone-sight,  how  common  ?     With  what  must  it  not  be  con  ounded  ?    Kind 

of  jrlasse*  for  efiort-fight  ?    Why  ?    Squint  ? 

82.  What  is- stated  in  connection  with  the  opera-glass?      Experiment  with 
pencil  and  distant  object  ? 


214  THE   SPECIAL  SENSES. 

ther  object  is  indistinct;  and  when  the  latter  is  seen 
clearly,  the  pencil  appears  indistinct ;  and  that  it  is  im- 
possible to  see  both  clearly  at  the  same  time.  Accordingly, 
the  eye  must  have  the  capacity  of  adjusting  itself  to  dis- 
tances, which  is  in  some  manner  comparable  to  the  action 
of  the  screw  of  the  opera-glass. 

83.  This,  which  has  been  called  the  function  of  accom- 
modation, is  one  of  the  most  admirable  of  all  the  powers 
of  the  eye,  and  is  exercised  by  the  crystalline  lens.  It 
consists  essentially  in  a  change  in  the  curvature  of  the 
front  surface  of  the  lens,  partly  through  its  own  elasticity, 
and  partly  through  the  action  of  the  ciliary  muscle. 


FIG.  52.— THE  FUNCTION  OP  ACCOMMODATION. 

The  right  half  of  the  diagram  shows  the  eye  at  rest.    The  left  half  shows  the  lens 
accommodated  for  near  vision. 

When  the  eye  is  at  rest,  that  is,  when  accommodated  for  a 
distant  object,  the  lens  is  flatter  and  its  curvature  dimin- 
ished (see  Fig.  52) ;  but  when  strongly  accommodated  for 
near  vision  the  lens  becomes  thicker,  its  curvature  in- 
creases, and  the  image  on  the  retina  is  made  more  sharp 
and  distinct.  Since  a  strong  light  is  not  required  in  view- 
ing near  objects,  the  pupil  contracts,  as  is  shown  in  the 
left-hand  half  of  the  diagram. 

83.  Function  of  accommodation  ?    Tn  what  does  it  consist  ?    How  is  the  func- 
tion explained  ? 


THE   SPECIAL    SENSES. 

84.  Old-sight,    or  Presbyopia. — But   this  marvel- 
lously beautiful  mechanism  becomes  worn  with  use;   or, 
more  strictly  speaking,  the  lens,  like  other  structures  of  the 
body,  becomes  harder  with  the  approach  of  old  age.     The 
material  composing  the  lens  becomes  less  elastic,  the  power 
to  increase  its  curvature  is  gradually  lost,  and  as  a  conse- 
quence, the  person  is  obliged  to  hold  the  book  further  away 
when  reading,  and  to  seek  a  stronger  light.    In  a  word,  the 
function  of  accommodation  begins  to  fail,  and  is  about  the 
first  evidence  that  marks  the  decline  of  life.    By  looking  at 
the  last  preceding  diagram,  and  remembering  that  the  in- 
creased curvature  of  the  lens  cannot  take  place,  it  will  be 
at  once  understood  why  old-sight  is  benefitted  in  near 
vision  by  the  convex  lens,  such  as  the  spectacles  of  old 
people  contain.    It  acts  as  a  substitute  for  the  deficiency 
of  the  crystalline  lens. 

85.  The  Sense  of  Hearing. — Sound. — Hearing,  or 
audition,  is  the  special  sense  by  means  of  which  we  are 
made  acquainted  with  sound.     What  is  sound?     It  is  an 
impression  made  upon  the  organs  of  hearing,  by  the  vibra- 
tions of  elastic  bodies.    This  impression  is  commonly  prop- 
agated by  means  of  the  air,  which  is  thrown  into  delicate 
undulations,   in   all   directions    from,  the  vibrating   sub- 
stance.   When  a  stone  is  thrown  into  smooth  water,  a  wave 
of  circular  form  is  set  in  motion,  from  the  point  where  the 
stone  struck,  which  constantly  increases  in  size  and  dimin- 
ishes in  force,  as  it  advances. 

86.  Somewhat  resembling  this,   is   the   undulation,  or 
sound-wave,  which  is  imparted  by  a  sonorous  vibration  to 
the  surrounding  atmosphere.     Its  shape,  however,  is  spher- 
ical, rather  than  circular,  since  it  radiates  upward,  down- 
ward, and  obliquely  as  well  as  horizontally,  like  the  wave 


84.  Change  of  sight  with  the  approach  of  old  age  ?    Explain  the  change  ? 

85.  Hearing  or  audition?      What  is  sound?      How  propagated   commonly.' 
Stone  thrown  in  water? 

86.  Sound-wave  in  the  atmosphere?    Its  shape?    Rate  of  motion  ?    Sound,  in 
water,  air,  and  solid  bodies  ? 


216  THE   SPECIAL   SENSES. 

in  water.  The  rate  of  motion  of  this  spherical  wave  of 
air  is  about  1050  feet  per  second,  or  one  mile  in  five 
seconds.  In  water,  sound  travels  four  times  as  fast  as  in 
air,  and  still  more  rapidly  through  solid  bodies ;  along  an 
iron  rod,  its  velocity  is  equal  to  two  miles  per  second. 

87.  The  earth,  likewise,  is  a  good  conductor  of  sound. 
It  is  said  that  the  Indian  of  our  western  prairies  can,  by 
listening  at  the  surface  of  the  ground,  hear  the  advance  of 
a  troop  of  cavalry,  while  they  are  still  out  of  sight,  and 
can  even  discriminate  between  their  tread  and  that  of  a 
herd  of  'buffaloes.      Solid  substances  also   convey  sounds 
with  greater  power  than  air.     If  the  ear  be  pressed  against 
one  end  of  a  long  beam,  the  scratching  of  a  pin  at  the, 
other  extremity  may  be  distinctly  heard,  which  will  not  be 
at  all  audible  when  the  ear  is  removed  from  the  beam. 
Although  air  is  not  the  best  medium  for  conveying  sound, 
it  is  necessary  for  its  production.     Sound  cannot  be  pro- 
duced in  a  vacuum,  as  is  shown  by  ringing  a  bell  in  the 
exhausted  receiver  of  an  air-pump,  for  it  is  then  entirely 
inaudible.     But  let  the  air  be  readmitted  gradually,  then 
the  tones  become  more  and  more  distinct,  and  when  the 
receiver  is  again  full  of  air,  they  will  be  as  clear  as  usual. 

88.  All  sonorous  bodies  do  not  vibrate  with  the  same 
degree  of  rapidity,  and  upon  this  fact  depends  the  pitch  of 
the  sounds  that  they  respectively  produce.     The  more  fre- 
quent the  number  of  vibrations  within  a  given  time,  the 
higher  will  be  the  pitch ;  and  the  fewer  their  number,  the 
lower  or  graver  will  it  be.     Now,  the  rate  of  the  successive 
vibrations  of  different  notes  has  been  measured,  and  it  has 
thus  been  found  that  if  they  are  less  than  sixteen  in  a 
second,  no  sound  is  audible;  while  if  they  exceed  60,000 
per  second  the  sound  is  very  faint,  and  is  painful  to  the 


87.  The  earth  as  a  conductor  of  sound  ?  To  what  has  the  western  Indian  been 
tautrht  ?  Solid  substances  as  conductors  ?  As  regards  sound,  in  what  respect  is 
air  necessary  ?  Sound  in  a  vacuum  ? 


THE   SPECIAL   SENSES.  21? 

ear.  The  extreme  limit  of  the  capacity  of  the  human  ear 
maybe  considered  as  included  between  these  points;  but 
the  sounds  which  we  ordinarily  hear  are  embraced  be- 
tween 100  and  3,000  vibrations  per  second. 

89.  The  ear,  which  is  the  proper  organ  of  hearing,  is  the 
most  complicated  of  all  the  structures  that  are  employed 
in  the  reception   of  external  impressions.     The  parts  of 
which  it  is  composed  are  numerous,  and  some  of  them  are 
extremely  small  and  delicate.     Nearly  all  these  parts  are 
located  in  an  irregularly  shaped  cavity  hollowed  out  in  the 
temporal,  or   "  temple,"  bone  of  each   side   of  the  head. 
That  part  of  the  bone  in  which  the  auditory  cavity  is 
placed  has  the  densest  structure  of  all  bones  of  the  body, 
and  has  therefore  been  called  the  "petrous,"  or  rocky  part 
of  the. temporal  bone.     In  studying  the  ear,  it  is  necessary 
to  consider  it  as  divided   into  three  portions,  which  are 
called,  from  their  relative  positions,  the  external  ear,  the 
middle  ear,  and  the  internal  ear.     (In  the  diagram,  Fig.  53, 
A,  the  first  is  not  shaded,  the  second  is  lightly  shaded,  and 
the  last  has  a  dark  background.) 

90.  The  External  Ear. — The  external  portion  of  the 
organ  of  hearing,  designated  in  Fig.  53,  A,  includes,  first, 
that  outer  part  (a),  which  is  commonly  spoken  of  as  "the 
ear,"  but  which  in  fact  is  only  the  portal  of  that  organ ; 
and,  secondly,  the  auditory  canal  (b).    The  former  consists 
of  a  fiat  flexible  piece  of  cartilage,  projecting  slightly  from 
the  side  of  the  head,  attached  to  it  by  ligaments,  and  sup- 
plied with  a  few  weak  muscles.     Its  surface  is  uneven,  and 
curiously  curved,  and  from  its  resemblance  to  a  shell,  it 
has  been  called  the  concha.     It  probably  serves  to  collect 
sounds,  and  to  give  them  an  inward  direction  ;  although 
its  removal  is  said  not  to  impair  the  acuteness  of  hearing 
more  than  a  few  days. 

9O.  Of  what  docs  the  external  portion  of  the  organ  of  hearing  consist?    De- 
scribe the  portal  of  that  organ  known  as  the  ear.    Its  use  ? 


218  THE   SPECIAL   SENSES. 

;. 

91.  In  those  animals  whose  hearing  is  more  delicate 
than  that  of  man,  the  corresponding  organ  is  of  greater 
importance,  it  being  larger  and  supplied  with  muscles  of 
greater  power,  so  that  it  serves  as  a  natural  kind  of  ear- 
trumpet,  which  is  easily  movable  in  the  direction  of  any 
sonnd^that  attracts  the  attention  of  the  animal.  Bold, 
predaceous  animals  generally  have  the  concavity  of  this 


FIG.  53.— THE  EAR  AND  ITS  DIFFERENT  PARTS. 

A.  Diagram  of  the  Ear. 

a,  b.  External  Ear.  d.  Middle  Ear. 

c,  Membrane  tympani.  e.  Internal  Ear. 

B  to  B"'.  Bones  of  the  Middle  Ear  (magnified). 
C,  The  Labyrinth?,  or  Internal  Ear  (highly  magnified). 

organ  directed  forward,  while  in  timorous  animals,  like  the 
rabbit,  it  is  directed  backward.  Fishes  have  no  outer  ear, 
but  sounds  are  transmitted  directly  through  the  solid  bones 
of  the  head,  to  the  internal  organ  of  hearing. 

92.  The  auditory  canal  (Fig.  53,  A,  b),  which  is  con- 
tinuous with  the  outer  opening  of  the  ear,  is  a  blind  pas- 
sage, an  inch  and  a  quarter  in  length,  its  inner  extremity 
being  bounded  by  a  closely-fitting,  circular  membrane. 
This  canal  is  of  oval  form,  is  directed  forward  and  inward, 

91.  The  car  in  the  animate  of  delicate  hearing!    Kabbit?    Fishes? 

92.  What  is  the  auditory  canal  ?    Describe  it. 


THE   SPECIAL   SENSES.  219 

and  is  slightly  curved;  so  that  the  inner  end  is  ordinarily 
concealed  from  view.  The  pouch  of  the  skin  which  lines 
this  passage  is  smooth  and  thin,  especially  at  the  lower 
end,  where  it  covers  the  membrane  just  mentioned. 

93.  As  in  the  case  of  the  nostrils,  a  number  of  small, 
stiff  hairs  garnish  the  margin  of  the  auditory  canal,  and 
guard  it,  to  some  extent,  against  the  entrance  of  insects 
and  other  foreign  objects.     The  skin,  too,  covering  its  outer 
half,  is  furnished  with  a  belt  of  little  glands  which  secrete 
a  yellow,  viscid,  and  bitter  substance,  called  "  ear-wax," 
which  is  especially  obnoxious  to  small  insects.     As  the 
outer  layer  of  this  wax-like  material  loses  its  useful  pro- 
perties, it  becomes  dry,  and  falls  out  of  the  ear  in  the  form 
of  minute,  thin  scales,  a  fresh  supply  being  furnished  from 
the  little  glands  beneath.     In  its  form,  the  auditory  canal 
resembles  the  tube  of  an  ear-trumpet,  and  serves  to  convey 
the  waves  of  sound  to  the  middle  portion  of  the  ear. 

94.  The  Middle  Ear,  or  Tympanum. — The  middle 
ear  is  a  small  cavity,  or  chamber,  of  irregular  shape,  about 
one-fourth  of  an  inch  across  from  side  to  side,  and  half  an 
inch  long  (see  Fig.  53,  A,  d).    From  the  peculiar  arrange- 
ment of  its  various  parts  it  has  very  properly  been  called 
the  tympanum,  or  the  "drum  of  the  ear."     The  middle 
ear,  like  the  external  canal,  contains  air. 

95.  The  circular  membrane,  already  mentioned  as  clos- 
ing the  auditory  canal,  is  the  partition  which   separates 
the  middle  from  the  external  ear,  and  is  called  the  mem- 
brana  tympani  (c),  and  may  be  considered  as  the  outer  head 
of  the  drum  of  the  ear.     It  is  sometimes  itself  spoken  of  as 
the  "  drum,"  but  this  is  incorrect ;  since  a  drum  is  not  a 
membrane,  but  is  the  hollow  space  across  which  the  mem- 
brane is  stretched.     This  membranous  drum-head  is  very 
tense  and  elastic,  and  so  thin  as  to  be  almost  transparent; 


93.  How  i*  it  guarded  and  protected  ?    Ear-wax  ? 

94.  What  is  the  middle  ear  'i    Why  called  tympanum  ? 

95.  What,  is  the  membraua  tympani  ?     Describe:  it. 


220  THE   SPECIAL   SENSES. 

its  margin  is  fastened  into  a  circular  groove  in* the  adjacent 
bone.  Each  wave  of  sound  that  impinges  against  this 
delicate  membrane  causes  it  to  vibrate,  and  it,  in  turn, 
excites  movements  in  the  parts  beyond. 

96.  Within  the  tympanum  is  arranged  a  chain  of  re- 
markable "  little  bones,"  or  ossicles.     They  are  chiefly  three 
in  number,  and  from  their  peculiar  shapes  bear  the  follow- 
ing names:  malleus,  or  the  mallet;    incus,  or  the  anvil; 
and  stapes,  or  the  stirrup.     A  fourth,  the  smallest  bone  in 
the  body,  in  early  life  intervenes  between  the  incus  and 
stapes,  but  at  a  later  period  it  becomes  a  part  of  the  incus. 
It  is  called  the  orbicular  bone.     Small  as  are  these  ossicles — 
and  they,  together,  weigh  only  a  few  grains — they  have 
their  little  muscles,  cartilages,  and  blood-vessels,  as  per- 
fectly arranged  as  the  larger  bones  of  the  body.     One  end 
of  the  chain  of  ossicles,  the  mallet,  is  attached  to  the  mem- 
brane, of  the  tympanum,  or  outer  drum-head,  while  the 
other  end,  the  stirrup,  is  firmly  joined  by  its  foot-piece  to 
a  membrane  in  the  opposite  side  of  the  cavity.     The  chain, 
accordingly,  hangs  suspended  across  the  drum  between  the 
two  membranes ;  and  when  the  outer  one  vibrates  under 
the  influence  of  the  sound-wave,  the  chain  swings  inward 
and  transmits  the  vibration  to  the  entrance  of  the  inner 
ear. 

97.  The  musical  instrument,  the  drum,  is  not  complete 
if  the  air  within  be  perfectly  confined :  we  therefore  find  in 
all  instruments  of  this  kind  a  small  opening  in  the  side, 
through  which  air  may  pass  freely.     By  this  means  the 
pressure  of  the  air  upon  the  vellum  which  forms  the  head 
of  the  drum  is  made  equal  upon  all  sides,  and  the  resonance 
of  the  drum  remains  unaffected  by  the  varying  density  of 
the  atmosphere.     It  will,  therefore,  emit  its  proper  sound, 
whether  it  be  struck  in  the  rarified  air  of  the  mountain- 
top,  or  in  the  condensed  air  of  a  mine.     The  tympanum, 

96.  What  are  the  ossicles  ?    Their  number  and  names  ?    Their  arrangement  ? 

97.  The  Eustachian  tube  ?    Describe  it,  and  state  its  use. 


THE    SPECIAL   SENSES. 


221 


or  drum  of  the  ear,  in  like  manner  has  an  opening  by 
means  of  which  it  communicates  freely  with  the  external 
air.  This  opening  is  a  narrow  canal,  about  an  inch  and  a 
half  long,  called  the  Eustachian  tube,  after  the  name  of  its 
discoverer,  Eustachius.  _^. 

98.  The  course  of  this  passage  is  indicated  in  Fig.  54,  i, 
directed  downward  and  inward:  its  other  extremity  opens 
into  the  upper  part  of  the  throat.  The  passage  itself  is 


FIG.  54.— SECTION  or  THE  RIGHT  EAR. 

A,  The  Concha.  E,  Incus,  or  Anvil. 

B,  Auditory  Canal.  M,  Malleus,  or  Mallet. 

C,  Membrane  of  the  Drum,  I,  Eustachian  Tube. 

(the  lower  half.)          -  G,  Semicircular  Canals. 

D,  A  small  muscle.  H,  Cochlea,  or  snail's  shell. 

ordinarily  closed,  but  whenever  the  act  of  swallowing  or 
gaping  takes  place,  the  orifice  in  the  throat  is  stretched 
open,  and  the  air  of  the  cavity  of  the  tympanum  may  then 
be  renewed.  Air  may  at  will  be  made  to  enter  through 
this  tube,  by  closing  the  mouth  and  nose,  and  then  trying 


98.  What  can  you  state  of  the  action  of  the  Eustachian  tube  ? 


222  THE   SPECIAL   SENSES. 

to  force  air  through  the  latter.  When  this  is  done,  a  dis- 
tinct crackle  or  clicking  sound  is  perceived,  due  to  the 
movement  of  the  membranes,  and  of  the  little  bones  of  the 
ear. 

99.  The  Eustachian  tube  serves,  also,  as  an  escape-pipe 
for  the  fluids  which  form  within    the  middle  ear;    and 
hence,  when  its  lining  membrane  becomes  thickened,  in 
consequence  of  a  cold,  or  sore  throat,  and  the  passage  is 
thus  more  or  less  choked  up,  the  fluids  are  unable  to  escape 
as  usual,  and  therefore  accumulate  within  the  ear.     When 
this  takes  place,  the  vibrations  of  the  membrane  are  inter- 
fered with;  the  sounds  heard  appear  muffled  and  indis- 
tinct;   and   a  temporary  difficulty  of  hearing,  which   is 
known  as  "throat-deafness,"  is  the  result.     This  result  re- 
sembles the  effect  produced  by  interrupting  the  vibrations 
of  a  sonorous  body,  such  as  all  are  familiar  with ;  if  the 
finger  be  placed  upon  a  piano-string  or  bell  when  it  is 
struck,  the  proper  -sound  is  no  longer  fully  and  clearly 
emitted.     But  the  primary  use  of  this  tube  is  to  afford  a 
free  communication  between  the  middle  ear  and  the  exter- 
nal atmosphere,  and  thus  secure  an  equal  pressure  upon 
both  sides  of  the  membrane  of  the  drum  of  the  ear,  however 
the  density  of  the  atmosphere  may  vary.     If,  from  undue 
tension  of  the  membranes,  pain  is  experienced  in  the  ears, 
when  ascending  into  a  rare  atmosphere,  as  in  a  balloon,  or 
descending  into  a  dense  one,  as  in  a  diving-bell,  it  may  be 
relieved  by  repeating  the  act  of  swallowing,  from  time  to 
time,  in  order  that  the  inner  and  outer  pressure  may  thus 
be  promptly  equalized. 

100.  The  Internal  Ear,  or  Labyrinth.— The  most 
essential  part  of  the  organ  of  hearing  is  the  distribution  of 
the  auditory  nerve.     This  is  found  within  the  cavity  of  the 
internal  ear,  which,  from  its  exceedingly  tortuous  shape, 


99.  What  other  purpose  does  the  Eustachian  tube  serve  *    How  is  this  shown  ? 
"  Throat-deafness*  *"    Primary  use  of  the  Eustachian  tube  ? 

100.  The  essential  part  of  the  organ  of  hearing  ?    Its  location  ?    Formation  ? 


THE   SPECIAL   SENSES.  223 

has  been  termed  the  labyrinth  (see  Fig.  53,  c).  This 
cavity  is  hollowed  out  in  dense  bone,  and  consists  of  three 
parts;  the  vestibule  (a),  or  ante-chamber,  which  is  connected 
with  the  other  two ;  the  cochlea  (b),  or  snail's  shell ;  and  the 
three  semicircular  canals  (c).  The  manner  in  which  the 
nerve  of  hearing  is  distributed  is  remarkable,  and  is  pecu- 
liar to  this  nerve.  In  the  vestibule  and  the  canals  its 
fibres  are  spread  out  over  the  inner  surface,  not  of  the  bony 
cavity  but  of  a  membranous  bag,  which  conforms  to  and 
partially  fills  that  cavity;  and  which  floats  in  it,  being 
both  filled  and  surrounded  with  a  clear,  limpid  fluid. 

101.  A  singular  addition  to  the  mechanism  of  hearing  is 
observed  within  this  membranous  bag  of  the  labyrinth 
This  consists  of  two  small  oval  ear-stones,  and  a  quantity 
of  fine  powder  of  a  calcareous  nature,  which  is  called  "£ar- 
sand."     When  examined  under  the  microscope,  these  sandy 
particles  are  seen  to  lie  scattered  upon  and  among  the 
delicate  filaments  of  the  auditory  nerve;  and  it  is  probable, 
that  as  the  tremulous  sound-wave  traverses  the  fluid  of  the 
vestibule,  the  sand  rises  and  falls  upon  the  nerve  filaments, 
and  thus  intensifies  the  sonorous  impression. 

102.  In, the  cochlea,  or  snail's  shell,  which  contains  the 
fluid,  but  no  membrane,  the  nerve  ramifies  upon  a  spiral 
shelf,  which,  like  the  cochlea  itself,  takes  two  and  a  half 
turns,  growing  continuously  smaller  as  it  winds  upward. 
As  many  as  three  thousand  nerve  fibres  of  different  lengths 
have  been  counted  therein ;  which,  it  has  been  thought, 
form  the  grand,  yet  minutely  small  key-board,  upon  which 
strike  all  the  musical  tones  that  are  destined  to  be  con- 
veyed to  the  brain.    The  vestibule,  it  is  also  supposed,  takes 
cognizance  of  noise  as  distinguished  from  musical  sounds; 
while  the  office  of  the  semicircular  canals  is,  in  part  at 
least,  to  prevent  internal  echoes,  or  reverberations. 


101.  Where  i?  the  "ear-sand11  found  1    Give  the  theory  as  to  its  use. 

102.  In  the  cochlea  or  snail1*  shell  ?    '-Key-board1'  in  the  internal  ear?    The 
vestibules  ?    Semicircular  canals  *> 


THE    SPECIAL    SKN 


103.  The    vestibule   communicates    with    the   chain  of 
bones  of  the   middle  ear  by  means   of  a   small  open  ing, 
called  the  "oval  wfadow,"  or/emfaa  oralis.    Across  this 
window   is   stretched    the    membrane,  which    has  already 
been  alluded  to  as  being  joined  to  the  stirrup-bone  of  the 
middle  ear.     Through  this  window,  then,  the  sound-wave. 
which  traverses  the  external  and  middle  ear,  arrives  at  last 
at  the  labyrinth.     The  limpid  fluid  which  the  latter  con- 
tains, and  which  bathes  the  terminal  fibres  of  the  nerve  of 
hearing,  is  thus  agitated,  the  nerve-fibres  are  excited,  and 
a  sonorous  impression  is  conducted  to  the  brain,  or,  as  we 
say,  a  sound  is  heard. 

104.  Protection  of  the  Sense  of  Hearing.—  From 
what  has  been  seen  of  the  complicated  parts  which  com- 
pose the  organ  of  hearing,  it  is  evident  that  while  many 
of  them  possess  an  exquisite  delicacy  of  structure,  Nature 
has  well   and  amply  provided  for  their  protection.     We 
have  observed  the  concealed  situation  of  the  most  impor- 
tant parts  of  the  mechanism  of  the  ear,  the  length  of  its 
cavity,  its  partitions,  the  hardness  of  its  Avails,  and  its 
communication  with  the  atmosphere;  all  these  provisions 
rendering  unnecessary  any  supervision  or  care  on  our  part 
in  reference  to  the  interior  of  the  ear.     But  in  respect  to 

.  ternal  parts,  which  are  under  our  control  and  within 
the  reach  of  harm,  it  is  otherwise.  We  may  both  observe 
the  dangers  which  threaten  them,  and  learn  the  means 
necessary  to  protect  them. 

105.  One  source  of  danger  to  the  hearing  consists  in 
lowering    the    temperature    of  the  ear,  especially    by    the 
introduction  of  cold  water  into  the  auditory  canal.     Every 
one  is  familiar  with  the  unpleasant  sensation  of  distension 
and  the  confusion  of  sounds  which  accompany  the  filling 
of  the  ear  with  water  when  bathing:  the  weight  of  the 

1OS.  With  what  doo*  tin-  vestibule  communicate?     What  is  the  theory  bv 
\\hich  sound  is  conducted  to  the  brain? 

104.  The  formation  of  the  onran  of  hearing  with  a  view  to  it*  protection? 

105.  Danger  to  which  tin-  hearing  may  be  "subjected  ?     Ae.\ 


THE  SPECIAL   BENSB8,  225 

water  within  it  ivally  distends  tho  membrane,  and  the  cold 
chills  tho  adjacent  sensitive  pans.  It  is  not  surprising, 
therefore,  that  the  frequent  introduction  of  cold  water  and 
its  continued  presence  in  the  ear  enfeeble  the  souse  of 
hearing,  (/are  >liould  ho  takon  to  remove  water  from  the 
oar  a  ft  or  bathing,  by  hold  ing  the  head  on  one  side,  and, 
at  the  same  time,  slightly  expanding  the  outer  orifice,  so 
that  the  ilnid  may  run  out.  For  a  like  reason,  the  hair 
about  the  oars  should  not  be  allowed  to  remain  wet,  but 
should  be  thoroughly  dried  as  soon  as  possible. 

106.  It  may  be  stated  as  a  general  rule,  to  which  there 
are  but  tow  exceptions,  that  no  cold  liquid  should  ever  be 
allowed  to  enter  the  ear.     When  a  wash  or  injection  is 
rendered  necessary,  it  should  always  be  warmed  before  use. 
The  introduction  of  cold  air  is  likewise  hurtful,  especially 
when  it  pours  through  a  crevice  directly  into  the  ear,  as  it- 
may  often  do  through  the  broken  or  partially  closed  win- 
dow of  a  car.     The  avoidance  of  this  evil  gives  rise  to 
Another  almost  as  great ;  namely,  the  introduction  of  cot- 
ton or  other  soft  substances  into  the  ear  to  prevent  it  from 
"catching  cold."    This  kind  of  protection  tends  to  make 
the  part  unnaturally  susceptible  to  changes  of  tempera- 
ture, and  its  security  seems  to  demand  the  continued  pres- 
ence of  the  "  warm"  covering.    As  a  consequence  of  its 
presence,  sounds  are  not  naturally  conveyed,  and  the  sen- 
sit  iveness  of  the  nerve  of  hearing  is  gradually  impaired. 

107.  The  chief  source  of  injury,  however,  to  the  ear  is 
from  the  introduction  of  solid  substances  into  the  auditory 
canal,  with  the  design  of  removing  insects  or  other  foreign 
objects  that  have  found  their  way  into  the  ear;  or  with 
the  design  of  scraping  out  the  ear-wax.     For  displacing  a 
foreign  object,  it  is  usually  sufficient  to  syringe  the  ear 
gently  with  warm  water,  the  head  being  so  held  that  the 


106.  The  ereneral  rnle  as  to  the  use  of  water  for  the  ear? 

107.  Chief  nonrco  of  injury  to  the  ear?    Directions  for  removing  foreign  ob- 
ject? from  the  ear  ?    Of  a  live  insect  ? 

10* 


226 


THE   SPECIAL   SENSES. 


fluid;  easily  escapes.  If  a  live  insect  has  gained  entrance 
to  the  ear,  it  may  first  be  suffocated  by  pouring  a  little  oil 
upon  it,  and  afterward  removed  by  syringing  the  ear  as 
just  mentioned. 

108.  The^rp&oval  of  ear-wax  is  generally  unnecessary; 
for,  as  we  havVbefore  seen,  Nature  provides  that  the  excess 
of  it  shall  become  dry,  and  then  spontaneously  fall  out  in 
the  form  of  fine  scales.  The  danger  from  the  introduction 
of  solid  implements  into  the  outer  ear  is  chiefly  found  in 
the  fact  that  the  membrane  which  lies  at  the  bottom  of  it 
is  very  fragile,  and  that  any  injury  of  it  is  liable  to  be  per- 
manent, and  to  permanently  impair  the  hearing  of  the 
injured  ear. 


QUESTIONS  FOR  TOPICAL  REVIEW. 

Give  a*  full  statements  as  yon  can  on  the  following  subjects  : 


1.  Production  of  sensation 177,  178 

2.  Variety  of  sensations 178,  179 

3.  General  sensibility 179,  180 

4.  The  sensation  of  pain 180 

5.  The  uses  of  pain 180,  1S1,  182 

6.  Special  sensation 182,  183 

7.  Orirans  of  touch 183.  1.W4 

8.  The  sense  of  touch 184,  185,  186 

9.  The  delicacy  of  tonch 186.  1S7 

10.  Sensations  of  temperature  and 

weight 187,  188 

11.  The  orsran  of  taste 188,  1!^ 

12.  The  sense  of  taste 189,  191 

13.  Relations  of  taste,  etc 190,  191 

14.  Influence  of  education,  etc.. 191.  19) 

15.  The  sense  of  smell 192,  193 

16.  The  nerve  of  smell 193,  194 

17.  Uses  of  the  sense  of  smell.  .194,  195 
IS.  The  sense  of  sight 196,  197 


19.  Lisrht.  and  the  optic  nerve.  .197,  198 

20.  The  organ  of  sight 19S,  199 

21.  The  orbits 199 

22.  The  eyelids 200,  201 

23.  The  lachrymal  fluid 201.  202.  203 

24.  The  eyeball 2(3.  204 

25.  The  iiis 2(>5.  206 

26.  The  retina 206,  207,  2(  8.  209 

27.  The  crystalline  lens 209,  210 

28.  Uses  of  the  lens 210,211.  212 

29    Lon?  and  short  sight 212,  213 

30.  Function  of  accommodatioii.213,  214 

31.  Old  sight,  or  presbyopia 215 

32.  Hearing  and  sound'. ...  .215.  216,  217 
83.  The  external  ear 217.  218.  219 

34.  The  middle  ear 219—222 

35.  The  internal  ear 222.  223,  "224 

36.  Protection  of  the  sense  of  hear- 

ing  224,  225,  226 


THE   VOICE. 


CHAPTER  XI. 

THE  VOICE. 

Voice  and  Speech — The  Larynx,  or  Hie  Organ  of  the  Voice — The  Vovil 
Cords— The  Laryngoscope— The  Production  oftJie  Voice— The  Use 
of  the  Tongue— The  different  Varieties  of  Voice— The  Change  of 
Voice — Its  Compass— Purity  of  Tone —  Ventriloquy. 

1.  Voice  and  Speech. — In  common  with  the  majority 
of  the  nobler  animals,  man  possesses  the  power  of  uttering 
sounds,  which  are  employed  as  a  means  of  communication 
and   expression.      In   man,    these   sounds   constitute   the 
voice ;  in  th&  animals,  they  are  designated  as  the  cry.     The 
song  of  the  bird  is  a  modification  of  its  cry,  which  is  ren- 
dered possible  from  the  fact  that  its  respiratory  function  is 
remarkably  active.     The  sounds  of  the  animals  are  gener- 
ally, but  not  always,  produced  by  means  of  their  breathing 
organs.     Among  the  insects,  they  are  sometimes  produced 
by  the  extremely  rapid  vibrations  of  the  wings  in  the  act 
of  flight,  as  in  the  case  of  the  musquito ;  or  they  are  pro- 
duced by  the  rubbing  together  of  hard  portions  of  the 
external  covering  of  the  body,  as  in  the  cricket.     Almost 
all  kinds  of  marine  animals  are  voiceless.     The  tambour- 
fish  and  a  few  others  have,  however,  the  power  of  making 
a  sort  of  noise  in  the  water. 

2.  But  man  alone  possesses  the  faculty  of  speech,  or  the 
power  to  use  articulate  sounds  in  the  expression  of  ideas, 
and  in  the  communication  of  mind  with  mind.     Speech  is 
thus  an  evidence  of  the  superior  endowment  of  man,  and 
involves  the  culture  of  the  intellect.     An  idiot,  while  he 

1 .  The  uttering  of  sounds  by  animals  ?    How  produced  ? 

2.  The  evidence  of  man's  superior  endowment?    What  is  stated  of  the  idiot? 
Parrot  ?    Raven  ? 


228  THE   VOICE. 


may  have  complete  vocal  organs  and  full  power  of  uttering 
sounds  or  cries,  is  entirely  incapable  of  speech ;  and,  as  a  rule, 
the  excellence  of  the  language  of  any  people  will  be  found 
to  be  proportional  to  their  development  of  brain.  Man, 
however,  is  not  the  only  being  that  has  the  power  to  form 
articulate  sounds,  for  the  parrot  and  the  raven  may  also 
Ibe  taught  to  speak  by  rote ;  but  man  alone  attaches  mean- 
ing to  the  words  and  phrases  he  employs. 

3.  Speech  is  intimately  related  to  the  sense  of  hearing, 
A  child  born  deaf  is,  of  necessity,  dumb  also;  not  because 
the  organs  of  speech  are  imperfect,  for  he  can  utter  cries 
and  may  be  taught  to  speak,  and  even  to  converse  in  a 
rude  and  harsh  kind  of  language ;    but   because  ,he  can 
form  no  accurate  notion  of  sound.     And  a  person,  whose 
hearing  is  not  delicate,  or  as  it  is  commonly  expressed, 
who  "has  no  ear  for  music,"  cannot  sing  correctly.     A  per- 
son who  has  impaired  hearing  commonly  talks  in  an  un- 
naturally loud  and  monotonous  voice.     These  examples 
show  the  necessary  relation  of  intelligence  and  the  sense 
of   hearing  with  that  form  of  articulate  voice,  which  is 
termed  speech. 

4.  The  Organ  of  the  Voice.— The  essential  organ 
of  the  voice   is  the   Larynx.      This  has  been  previously 
alluded  to  in  its  relation  to  the  function   of  respiration  ; 
and,  in  the  chapter  on  that  subject,  are  figured  the  front 
view  of  that  organ  (Fig.  35),  and  its  connection  with  the 
trachea,  tongue,  and  other  neighboring  parts  (Fig.  38).    It 
is  situated  at  the  upper  part  of  the  neck,  at  the  top  of  the 
trachea,  or  tube  by  which  air  passes  into  and  out  of  the 
lungs.     The  framework  of  the  larynx  is  composed  of  four 
cartilages,  which   render  it  at  once  very  strong  and  suffi- 
ciently flexible  to  enable  it  to  move  according  to  the  re- 
quirements of  the  voice. 

3.  Speech  and  hearing?    A  deaf  child?    Person  having  "no  ear  for  music?1' 
Impaired  hearincr  ?    What  do  the  examples  show? 

4.  Orjpin  of  the  voice  ?    Where  situated  ?    Of  what  is  its  framework  composed  ? 


THE   VOICE. 


5.  The   names  of  -the   cartilages  are  (1)    the  thyroid, 
which  is  a  broad  thin  plate,  bent  in  the  middle  and  placed 
in  the  central  line  of  the  front  part  of  the  neck,  where  it 
is  known  as  the  pomum  Adami,  or 

Adam's  apple  (Fig.  55,  B),  and 
where  it  may  be  felt  moving  up 
and  down  with  each  act  of  swal- 
lowing; (2)  the  cricoid,  which  is 
shaped  like  a  seal  ring,  with  the 
broad  part  placed  posteriorly  (Fig. 
55,  E).  At  the  top  of  the  cricoid 
cartilage  are  situated  the  two  small 
arytenoid  cartilages,  the  right  one 
of  which  is  shown  in  Fig.  55,  c. 
These  latter  little  organs  are  much 
more  movable  than  the  other  two, 
and  are  very  important  in  the  pro- 
duction of  the  voice.  They  have 
a  true  ball  and  socket  joint,  and 
several  small  muscles  which  con- 
tract and  relax  with  as  perfect  regu- 
larity and  accuracy  as  an-y  of  the 
larger  muscles  of  the  body. 

6.  The  interior  of  the  larynx  is  SECTION  °?r™^AulYNX  AND 
lined  with  a  very  sensitive  mucous  ^; 

membrane,  which  is  much  more  g, 
closely  adherent  to  the  parts  be-  f ; 
neath  than  is  usually  the  case  with  H'  The  Trachea- 
membranes  of  this  description.  The  epiglottis  (A),  con- 
sisting of  a  single  leaf-shaped  piece  of  cartilage,  is  attached 
to  the  front  part  of  the  larynx.  It  is  elastic,  easily  moved, 
and  fits  accurately  over  the  entrance  to  the  air-passages 
below  it.  Its  office  is  to  guard  these  delicate  passages  and 
the  lungs  against  the  intrusion  of  food  and  other  foreign 


5.  Names,  formation,  and  situation  of  the  eartilasres  ? 

6,  Lining  of  the  interior  of  the  larynx  ?     The  epiglottis  ? 


230  THE   VOICE. 


articles,  when  the  act  of  swallowing  takes  place.     It  also 
assists  in  modifying  the  voice. 

7.  The  Vocal  Cords.  —  Within  the  larynx,  and  stretched 
across  it  from  the  thyroid  cartilage  in  front  to  the  aryte- 
noid  cartilages  behind,  are  placed  the  two  sets  of  folds, 
called  the  vocal  cords.     The  upper  of  these,  one  on  each 
side,  are  the  false  cords,  which  are  comparatively  fixed  and 
inflexible.     These  are  not  at  all  essential  to  the  formation 
of  vocal  sounds,  for  they  have  been  injured,  in  those  lower 
animals  whose  larynx  resembles  that  of  man,  without  ma- 
terially affecting  their  characteristic  cries.     Below  these, 
one  on  each   side,  are   the  true   vocal  cords    (Fig.  55,  F), 
which  pursue  a  similar  direction  to  the  false  cords,  namely, 
from  before  backward.     But  they  are  composed  of  a  highly 
elastic,  though  strong  tissue,  and  are  covered  with  a  thin, 
tightly-fitting  layer  of   mucous  membrane.     Their  edges 
are  smooth  and  sharply  defined,  and  when  they  meet,  as 
they  do  in  the  formation  of  sounds,  they  exactly  match 
each  other. 

8.  Between  the  true  and  false  vocal  cords  is  a  depression 
on  each  side,  which  is  termed  the  ventricle  of  the  larynx 
(Fig.  55,  D).     The  integrity  of  these  true  cords,  and  their 
free  vibration,  are  essential  to  the  formation  of  the  tones 
and  the  modulation  of  the  natural  voice.     This  is  shown 
by  the  fact  that,  if  one  or  both  of  these  cords  are  injured 
or  become  diseased,  voice  and  speech  are  compromised; 
or  when  the  mucous  membrane  covering  them  becomes 
thickened,  in  consequence  of  a  cold,  the  vocal  sounds  are 
rendered  husky  and  indistinct.    When  an  opening  is  made 
in  the  throat  below  the  cords,  as  not  infrequently  happens 
in  consequence  of  an  attempt  to  commit  suicide,  voice  is 
impossible  except  when  the  opening  is  closed  by  external 
pressure. 


7»  Wh«-r(»  are  the  vocal  corrl<  ?     The  fnlsc  rrtrds?    The  true  cords? 
8.  Whcni  i*  the  ventricl«  of  the  larynx?    The  essentials  to  the  formation  of  the 
tones  and  modulation  of  the  voice  ? 


THE   VOICE.  231 


9.  The  interval  or  space  between  the  true  cords  of  the 
voice  is  constantly  varying,  not  only  when  their  vocal 
function  is  in  exercise,  but  also  during  the  act  of  respira- 
tion. Every  time  the  lungs  are  inflated,  the  space 
increases  to  make  wide  the  entrance  for  the  air;  and  dimin- 
ishes slightly  during  expiration.  So  that  these  little  cords 
move  gently  to  and  fro  in  rhythm  with  the  expansion  and 
contraction  of  the  chest  in  breathing.  These  movements 
and  others  may  be  seen  to  take  place,  if  a  small  mirror 
attached  to  a  long  handle  be  placed  back  into  the  upper 
part  of  the  throat;  the  handle  near  the  mirror  must  be 


FIG.  56. 
A  VIEW  or  THE  VOCAL  CORDS  BY  MEANS  op  THE  LARYNGOSCOPE. 

bent  at  an  angle  of  45°,  so  that  we  may  look  "around  the 
corner,"  so  to  speak,  behind  the  tongue.  The  position 
which  the  mirror  must  assume  will  be  understood  by 
reference  to  Fig.  38.  A  view  of  what  may  be  seen  under 
favorable  circumstances,  during  tranquil  inspiration  is 
represented  in  Fig.  56.  The  vocal  cords  are  there  shown  as 
narrow,  white  bands,  on  each  side  of  the  central  opening, 
and  since  the  image  is  inverted,  the  epiglottis  appears  up- 
permost. The  rings  partly  seen  through  the  opening  be- 
long to  the  trachea.  This  little  mirror  is  the  essential  part 


9.  Variation  in  the  interval  between  the  true  cords  of  the  voice?    Experiment 
with  the  mirror  ? 


232  THE    VOICE. 


of  an  instrument,  which  is  called  the  laryngoscope,  and, 
simple  as  it  may  seem,  it  is  accounted  one  of  the  most  val- 
uable of  the  recently  invented  appliances  of  the  medical 
art. 

10.  The  Production  of  the  Voice.— During  ordi- 
nary tranquil  breathing  no  sound  is  produced  in  the  lar- 
ynx, true  vocal  tones  being  formed  only  during  forcible 
expiration,  when,  by  an  effort  of  the  will,  the  cords  are 
brought  close  together,  and  are  stretched  so  as  to  be  very 
tense.  The  space  between  them  is  then  reduced  to  a 
narrow  slit,  at  times  not  more  than  -ffa  °f  an  ^nc^  in 
width  ;  and  the  column  of  expired  air  being  forced  through 
it  causes  the  cords  to  vibrate  rapidly,  like  the  strings  of  a 
musical  instrument.  Thus  the  voice  is  produced  in  its 
many  varieties  of  tone  and  pitch;  its  intensity,  or  loud- 
ness,  depending  chiefly  upon  the  power  exerted  in  expell- 
ing the  air  from  the  lungs.  When  the  note  is  high,  the 
space  is  diminished  both  in  length  and  width ;  but  when  it 
is  low,  the  space  is  wider  and  longer  (Fig.  57,  B,  c),  and 
the  number  of  vibrations  is  fewer  within  the  same  period 
of  time. 


FIG.  57. 

THE  DIFFLUENT  POSITIONS  OF  THE  VOCAL  CORDS. 

•    A,  The  position  during  inspiration.    B,    In  the  formation  of  low  notes. 
C,  In  the  formation  of  high  notes. 

11.  The  personal  quality  of  the  voice,  or  that  which  en- 
ables us  to  recognize  a  person  by  his  speech,  is  mainly  due 
to  the  peculiar  shape  of  the  throat,  nose,  and  mouth,  and 

10.  The  formation  of  true  vocal  tones  ? 

1 1 .  To  what  is  the  personal  quality  of  the  voice  mainly  due  ?    What  aids  are 
there  ? 


THE   YOICE.  233 


the  resonance  of  the  air  contained  within  those  cavities. 
The  walls  of  the  chest  and  the  trachea  take  part  in  the 
resonance  of  the  voice,  the  air  within  them  vibrating  at 
the  same  time  with  the  parts  above  them.  This  may  be 
tested  by  touching  the  throat  or  breast-bone,  when  a 
strong  vocal  effort  is  made.  The  teeth  and  the  lips  also 
are  important,  as  is  shown  by  the  unnatural  tones  emitted 
by  a  person  who  has  lost  the  former,  or  by  one  who  is 
affected  with  the  deformity  known  as  "hare-lip."  The 
tongue  is  useful,  but  not  indispensable  to  speech ;  the  case 
of  a  woman  is  reported,  from  whom  nearly  the  whole 
tongue  had  been  torn  out,  but  who  could,  nevertheless, 
sneak  distinctly  and  even  sing. 

'/  12.  The  varieties  of  voice  are  said  to  be  four  in  num- 
ber ;  two,  the  bass  and  tenor,  belonging  to  the  male  sex ; 
and  two,  the  contralto  or  alto,  and  soprano,  peculiar  to  the 
female.  The  baritone  voice  is  the  name  given  to  a  variety 
intervening  between  the  bass  and  tenor.  In  man,  the 
voice  is  strong  and  grave;  in  woman,  soft  and  high.  In 
infancy  and  early  youth,  the  voice  is  the  same  in  both 
sexes,  being  of  the  soprano  variety :  that  of  boys  is  both 
clear  and  loud,  and  being  susceptible  of  considerable  train- 
ing, is  highly  prized  in  the  choral  services  of  the  church 
and  cathedral.  At  about  fourteen  years  of  age  the  voice  is 
said  to  change  ;  that  is,  it  becomes  hoarse  and  unsteady  by 
reason  of  the  rapid  growth  of  the  larynx.  In  the  case  of 
the  girl,  the  change  is  not  very  marked,  except  that  the 
voice  becomes  stronger  and  has  a  wider  compass ;  but  in 
the  boy,  the  larynx  nearly  doubles  its  size  in  a  single  year, 
the  vocal  cords  grow  thicker,  longer,  and  coarser,  and  the 
voice  becomes  masculine  in  character.  During  the  prog- 
ress of  this  change,  the  use  of  the  voice  in  singing  is  inju  • 
dicious. 

13.  The  ordinary  range  of  each  of  the  four  varieties  of 


1 2.  Varieties  of  voice  ?    The  baritone  ?    The  voice  in  early  youth  ? 

1 3  j  The  rouge  of  the  voice  ?    Result  of  careful  training  of  the  vocal  organs  ? 


234  THE    VOICE. 


the  voice  is  about  two  octavos;  but  this  is  exceeded  in  the 
case  of  several  celebrated  vocalists.  Madame  Parepa-Rosa 
has  a  compass  of  three  full  octaves.  When  the  vocal  or- 
gans have  been  subjected  to  careful  training,  and  are 
brought  under  complete  control  of  the  will,  the  tension 
of  the  cords  become  exact,  and  their  vibrations  become 
exceedingly  precise  and  true.  Under  these  circumstances 
the  voice  is  said  to  possess  "purity"  of  tone,  and  can  be 
heard  at  a  great  distance,  and  above  a  multitude  of  other 
sounds.  The  power  of  a  pure  voice  to  make  itself  heard 
was  recently  exemplified  in  a  striking  manner  :  at  a  musi- 
cal festival  held  in  an  audience-room  of  extraordinary  size, 
and  amid  an  orchestra  of  a  thousand  instruments  and  a 
chorus  of  twelve  thousand  voices,  the  artist  named  above 
also  sang ;  yet  such  was  the  purity  and  strength  of  her 
voice  that  its  notes  could  be  clearly  heard  rising  above  the 
vast  waves  of  sound  produced  by  the  full  accompaniment 
of  chorus  and  orchestra. 

14.  In  the  production  of  the  articulate  sounds  of  speech, 
the  larynx  is  not  directly  concerned,  but  those  sounds 
really  depend  upon  alterations  in  the  shape  of  the  air- 
passages  above  that  organ.  That  speech  is  not  necessarily 
due  to  the  action  of  the  larynx  is  proven  by  the  following 
simple  experiment.  Let  an  elastic  tube  be  passed  through 
the  nostril  to  the  back  of  the  mouth.  Then,  while  the 
breath  is  held,  cause  the  tongue,  teeth,  and  lips  to  go 
through  the  form  of  pronouncing  words,  and  at  the  same 
time,  let  a  second  person  blow  through  the  tube  into  the 
mouth.  Speech,  pure  and  simple,  or,  in  other  words,  a 
whisper  is  produced.  Still  further  continue  the  experi- 
ment, while  permitting  vocal  sounds  to  be  made,  and  there 
will  be  produced  a  loci  and  whispering  speech  at  the  same 
moment;  thus  showing  that  voice  and  speech  are  the  re- 
sult of  two  distinct  acts.  Sighing,  in  like  manner,  is  pro- 


1 4.  The  production  of  the  articulate  sounds  ?    What  experiment  is  mentioned .» 


THE   VOICE.  235 


duced  in  the  mouth  and  throat;  if,  however,  a  vocal  sound 
be  added,  the  sigh  is  changed  into  a  groan. 

15.  Ventriloquism  is  a  peculiar  modification  of  natu- 
ral speech,  which  consists  in  so  managing  the  voice  that 
words  and  sounds  appear  to  issue,  not  from  the  person, 
but  from  some  distant  place,  as  from  the  chimney,  cellar, 
or  the  interior  of  a  chest.  The  original  meaning  of  the 
word  ventriloquism  (that  is,  speaking  from  the  belly),  in- 
dicates the  early  belief  that  this  mode  of  speech  was  de- 
pendent upon  the  possession  and  use  of  some  special  organ 
besides  the  larynx  and  mouth  ;  but  at  the  present  time,  it 
is  known  that  it  is  produced  by  these  organs  alone,  and 
that  the  sources  of  deception  consist  on  the  part  of  the 
performer,  in  the  dexterous  management  of  the  voice,  to- 
gether with  a  talent  for  mimicry;  and,  on  the  part  of  the 
auditory,  in  the  liability  of  the  sense  of  hearing  to  error  in 
respect  to  the  direction  of  sounds.  The  ventriloquist  not 
only  seems  to  "  throw  his  voice,"  as  it  is  said,  or  simulates 
the  sotind  as  it  usually  appears  at  a  distance  with  but  lit- 
tle motion  of  the  lips  and  face,  but  he  imitates  the  voices 
of  an  infant  and  of  a  feeble  old  man,  of  a  drunken  man 
disputing  with  an  exasperated  wife,  the  broken  language  of 
a  foreigner,  the  cry  of  an  animal  in  distress,  demonstrating 
that  the  performer  must  be  proficient  in  the  art  of  mimicry. 
Ventriloquism  was  known  to  the  ancient  Eomans  and 
Greeks ;  and  it  is  thought  that  the  mysterious  responses 
that  were  said  to  issue  from  the  sacred  trees  and  shrines 
of  the  oracles  at  Dodona  and  Delphi,  were  really  uttered 
by  priests  who  had  the  power  of  producing  this  form  of 
speech. 


15.  What  is  ventriloquism  ?    Indication  of  the  original  meaning  of  the  word  ? 
How  are  the  ventriloquous  sounds  produced  ? 


236  THE   MICROSCOPE. 


CHAPTER    XII. 

<* 

THE  USE  OF  THE  MICROSCOPE  IN  THE  STUDY  OF 
PHYSIOLOGY. 

1.  The  Law  of  the  Tissues. — The  will  of  an  infinite 
Creator  is  obeyed  by  atoms  as  well  as  by  worlds.     He  has 
seen  fit  to  commit  all  the  functions  of  life  to  structures  or 
tissues  so  small  as  to  be  invisible  to  the  naked  eye.     A 
muscle,  for  example,  as  we  have  already  learned,  is  com- 
posed of  innumerable  filaments,  visible  only  by  the  aid  of 
the  microscope;  and  the  power  of  the  muscular  mass  is 
but  the  sum   of  the  contractile  power  of  the   filaments 
which  enter  into  its  composition.     Again,  each  cell  of  the 
liver,  invisible  to  unassisted  sight,  is  a  secreting  organ,  and 
the  liver  performs  as  much  duty  as  the  sum  of  these  mi- 
nute organs  renders  possible  and  no  more. 

2.  The  Necessity  of  the  Microscope. — If,  there- 
fore, we  would   know  the  real  structure  of  the  human 
body,  we  must  make  use  of  the  microscope.     We  are  not  at 
liberty  either  to  use  it  or  not ;  we  must  have  recourse  to  it 
in  order  to  obtain  a  real  knowledge  of  the  human  body. 
Our  eyes  are  constructed  for  the  common  offices  of  life,  to 
provide  for  our  wants  and  guard  us  from  the  ordinary 
sources  of  danger ;  but  by  arming  them  with  lenses,  the 
real  structure  of  plants  and   animals  is  revealed  to  our 
intelligence ;  and  enemies,  otherwise  invisible,  that  lie  in 
wait  in  the  air  we  breathe,  and  in  our  daily  food  and  drink, 
to  destroy  life,  are  guarded  against, 

3.  Convex   lenses,   or  magnifying  glasses,   are  disks 
of  glass  or  other   transparent  substance,  which  have   the 


1 .  The  will  of  the  Creator,  by  what  obeyed  ?    The  power  of  a  muscle  ? 
Amount  of  duty  performed  by  the  liver? 

2.  Necessity  for  usinjr  the  microscope  ?    The  advantages  gained  by  its  use  ? 

3.  What  are  convex  lenses?    Kind  of  lenses  used  in  microscopes?    Experi- 
ment ?     Picture  thrown  upon  the  eye  ?    Derivation  of  the  word  microscope  * 


THE   MICROSCOPE.  237 

property  of  picturing  upon  the  retina  of  the  eye  an 
image  of  an  object  larger  than  the  image  produced  there 
without  their  aid.  The  glasses  used  in  microscopes  are 
either  double  convex  lenses  (a)  or  plano-convex  lenses  (b). 

b 


If  a  double  convex  lens  or  a  plano-convex  one  be  placed 
over  a  hole  in  the  shutter  of  a  darkened  room,  or  over 
the  key-hole  of  a  door,  and  a  piece  of  paper  be  held  at  a 
proper  distance,  a  picture  of  all  objects  in  front  of  the 
lens  will  be  thrown  on  the  paper,  as  in  the  camera-obscura 
or  the  magic-lantern.  Now,  in  the  same  manner,  a  lens 
throws  a  picture  of  objects  to  which  it  is  directed  on  the 
retina  of  the  eye,  and  when*that  picture  is  larger  than  the 
image  made  in  the  eye  by  the  object,  without  the  aid  of 
the  lens,  it  is  magnified,  or  the  lens  has  served  as  a  micro- 
scope, so  called,  from  its  use  in  seeing  small  objects,  from 
mikros,  small,  and  skopeo,  to  see. 

4.  Different  Kinds  of  Microscopes. — Microscopes 
are  either  simple  or  compound.     The  glasses  of  magnifying 
spectacles,  like  those  commonly  used  by  aged  persons,  are 
simple    microscopes.      Magnifying    glasses,    mounted    in 
frames  such  as  are  for  sale  by  opticians  and  others,  for 
the  detection  of  counterfeit  money,  are  simple  microscopes, 
and  are  useful  in  studying  the  coarser  structure  of  plants 
and  animals. 

5.  The  most  powerful  simple  microscopes  are  made  by 
melting  in  a  flame  a  thread  of  spun  glass,  so  as  to  form  a 


4.  Kinds  of  microscope  ?    What  are  simple  microscopes  ? 

5.  Construction  of  the  most  powerful  simple  microscopes?    In  practice?    A 
doublet ':    Triplet  ?    Why  are  compound  microscopes  superior  to  simple  ones  ? 


238  THE   MICROSCOPE. 


minute  globule  or  bead,  which,  when  set  in  a  piece  of 
metal  and  used  to  examine  objects  on  a  plate  of  glass  held 
up  to  the  light,  gives  a  high  magnifying  power.  In  prac- 
tice, however,  it  is  found  better  to  use  several  magnifying 
glasses  of  moderate  power,  than  a  simple  lens  alone  of 
high  power.  A  combination  of  two  lenses  is  called  a  doub- 
let—of  three,  a  triplet.  All  simple  microscopes  throw  an 
enlarged  image  of  the  object  upon  the  retina.  Compound 
microscopes  are  so  constructed  that  the  enlarged  image  of 
an  object  is  again  magnified  by  a  second  lens,  and  hence 
their  magnifying  power  is  vastly  superior  to  that  of  simple 
microscopes. 

6.  The  accompanying  diagrams  will  explain  the  action 
of  the  compound  microscope  compared  with  that  of  the 


FIG.  58.— SIMPLE  MICROSCOPE. 

simple  microscope.  In  Fig.  58,  which  represents  the  work- 
ing of  the  simple  microscope,  the  rays  from  the  object  (a  b), 
passing  through  the  lens  (L),  form  an  image  (a'  b')  in  the 
retina  of  the  eye  (E),  and  as  all  images  are  inverted  in  the 
eye,  the  object  is  seen  as  all  other  objects  are,  and  appears 
erect.  In  Fig.  59  is  seen  the  action  of  the  compound 
microscope.  An  inverted  image  (a'  V)  of  the  object  (a  b) 
is  magnified  by  the.  second  lens  (L'),  and  an  erect  image  is 
thrown  upon  the  retina,  which,  as  all  other  objects  seen 
erect  with  the  naked  eye  are  inverted,  gives  to  the  image 
a  contrary  direction,  or  inverts  it  to  the  mind. 

G.  Explain,  by  means  of  the  diagram,  the  action  of  the  compound  microscope. 


THE   MICROSCOPE. 


239 


7.  A  Compound  Microscope   consists   of  two  por- 
tions :  the  optical  portion,  or  the  lenses,  and  the  mechanical 
portion,  or  the  instrument  which  bears 

*  ,^-3BP»     >  fv      M 

the  lenses.  The  glasses  of  a  compound 
microscope  are  two :  the  object-glass  (D), 
Fig.  60,  and  the  lower  lens  of  Fig.  59, 
and  the  ocular  or  eye-piece  (A),  Fig.  60, 
and  the  upper  piece  of  Fig.  59.  Both 
the  object-glass  and  the  eye-piece  may, 
and  usually  do,  consist  of  more  than 
one  lens,  for,  as  previously  mentioned, 
better  results  are  obtained  by  a  com- 
bination of  lenses  of  moderate  power 
than  by  single  lenses  of  high  power 
and  great  curvature. 

8.  How  to  choose  and  use   a 
Microscope. — No  attractiveness   in 
the  mechanical  part  of  a  microscope 
can   compensate    for    inferior   lenses; 
and  the  very  first  consideration  in  the 
choice  of  an  instrument  should  be  the 
excellence  of  the  optical  part  of  the 
instrument.     In  the  use  of  the  instru- 
ment, care  should  be  exercised  to  keep 
the  lenses  clean,  free  from  dust,  not  to 
press  the  object-glass   upon  the  object 
under  observation,  and  not  to  wet  it 
in  the  water  in  which  most  objects  are 
examined.      A    good    microscope    re- 
quires its  own  table  ;    and  when  not 
in   use,  should  be   covered   by  a  bell 
glass  or  a  clean  linen  cloth. 

9.  The   mechanical  portion   of  the   instrument  varies 

7,  Portions,  in  a  compound  microscope  ?    The  glasses  ? 

8.  How  to  choose  a  microscope  ?    How  to  use  it? 

il.  The  characteristics  of  the  best  instrument?    What  special  requisites  should 
be  insisted  upon  ?    Why,  as  to  a  horizontal  stage  ? 


FIG.  59. 
COMPOUND  MICROSCOPE. 


240 


THE    MICROSCOPE. 


greatly  in  different  instruments.  That  one  is  the  best 
which  is  simplest,  the  most  solid  and  easily  managed. 
The  stage  (E),  upon  which  the  object  is  pla?3<i>  should 


A,  Eye-piece. 

B,  Body. 

C,  Collar. 

D,  Object-glass. 


FIG 


E,  Stage. 

F,  Hinire. 

G,  Mirror. 
H,  Stand. 


not   be   movable :   it   should    be    solid    and   firm.      The 
screw  by  which  the  focal  distance  is  adjusted,  and  which 


THE    MICROSCOPE. 


241 


is  in  constant  use,   should  be  so  placed  that  it   can  be 
worked  by  the  hand  resting  on  the  table:   otherwise  fa- 


FIG.  61. 

tigue  is  soon  induced.     The  direction  of  the  tube  carry- 

11 


242  THE   MICROSCOPE. 


ing  the  glasses  should  be  perpendicular,  and  the  stage 
therefore  horizontal.  Most  objects  in  human  anatomy  are 
examined  in  Avater  or  in  other  liquids,  or  they  are  them- 
selves liquids;  hence  an  oblique  stage  is  often  incon- 
venient. 

10.  Additional  Apparatus. — As  almost  all  objects 
in   human   anatomy  are   examined  by  transmitted   light 
thrown  up  from  the  mirror  (G,  Fig.  60)  beneath  the  stage 
through  the  object  to  the  eye,  they  must  be  placed  upon 
strips  of  clear  glass  about  three  inches  long  and  one  inch 
wide,  commonly  called  '''slides."     These  should  be  pro- 
cured with  the  microscope.     Again,  most  objects  seen  with 
high  powers  require  to  be  covered  with  a  thin  plate  of 
glass,  very  properly  called  a  "  cover,"  that  the  moisture  of 
the  specimen  may  not  tarnish  the  object-glass.     Square  or 
circular  covers  of  very  thin  glass  are  therefore  provided ; 
and  a  good  supply  of  these  should  be  always  on  hand. 
These  glasses  should  be  kept  in  a  covered  dish  filled  with 
a  mixture  of  alcohol  and  water.     Simple  water  will  not  re- 
move the  fatty  matter  which  exists  in  all  animal  tissues, 
and,  therefore,  the  glasses  cannot  be  thoroughly  cleaned 
with  it  alone. 

11.  When  glasses  are  required  for  use,  they  should  be 
removed  from  the  liquid  and  wiped  clean  and  dry  with  a 
soft  linen  handkerchief.     Delicate  knives,  scissors,  needles 
mounted  in  handles,  forceps,   pipettes  or  little  tubes  for 
taking  up  water,  should  be  obtained;  these  are  essential  to 
all  microscopical  study.     The  table  should  be  supplied  with 
glass-stoppered  bottles  containing  the  various  liquids  or- 
dinarily used  in  the  study  of  physiology.     Thus,  tincture 
of  iodine  is  indispensable  in  studying  vegetable  structure, 
acetic  acid  in  the  study  of  animal  tissues;  and  other  articles 
will  have  to  be  added  from  time  to  time,  as  your  progress 
in  study  demands  them. 

10.  Slides  ?    Covers,  square  and  circular?    How  kept? 

11.  Cleaning  the  glasses  ?    Knives,  scissors,  etc.  ?     various  liquids? 


THE   MICROSCOPE.  243 

12.  Preliminary  Studies. — In  order  to  prepare  the 
way  for  the  study  of  any  department  of  science  with   the 
aid  of  the  microscope — for  the  microscope  is  but  an  eye,  and 
can  be  turned  in  almost  any  direction  for  purposes  of  in- 
vestigation— it  is  necessary  to  become  acquainted  with  the 
many  objects  which  are  liable  to  complicate  the  examina- 
tion of  particular  structures.     Botli  air  and  water  are  full 
of  floating  bodies,  and  the  most  common  of  these  should 
first  occupy  the  attention.     In  the  city,  particles  of  starch 
are  always  floating  in  the  air.     Take  a  very  minute  portion 
of  wheat  flour,  place  it  in  the  middle  of  a  clean  glass  "  slide," 
drop  upon  it  a  drop  of  pure  water,  cover  it  with  a  plate 
of  thin  glass,  and  examine  it  with  a  power  of  from  one 
hundred  to  six  hundred  diameters.     It  will  be  found  to  be 
composed  of  minute  grains  or  granules,  the  largest  of  which 
are  made  up  of  coats  or  layers,  like  an  onion,  arranged 
around  a  central  spot  called  the  hilum. 

13.  Make  another  preparation  in  the  same  manner,  and, 
after  adding  the  water  and  before  covering  with  the  thin 
glass   cover,  add   a   small    drop  of   a  solution  of  iodine. 
Now,  upon  examining  the  specimen,  every  grain  will  be 
seen  to  be  of   a  beautiful  deep   blue  color.      After  thus 
studying  wheat  starch,  the  starch  of  Indian  corn,  of  arrow- 
root, and  of  various  grains  should  be  examined  in  like  man- 
ner, and  their  resemblances  and  differences  noted.     The 
granules  of  potato-starch  are  as  distinctly  marked  as  any. 
(See  Fig.  15,  page  61.) 

14.  Fibres  of  cotton,  lint,  and   wool  are   liable   to  be 
found  in  every  specimen  prepared  for  microscopical  exami- 
nation.    In  order  to  study  these,  any  cotton,  woollen,  or 
linen  fabric,  or  garment,  may  be  scraped,  and  the  scrap- 
ings placed  on  a  piece  of  glass  moistened  with  water,  cov- 
ered with  the  thin  glass  plate  or  cover  as  before,  and  exam- 

1  2.  Bodies,  in  air  and  water  ?    The  examination  of  starch  ? 

13.  The  examination  with  solution  of  iodine?    Advice  respecting  other  arti- 
cles ? 

14.  Directions  for  examining  cotton  and- other  fibres  ?    Vegetable  hairs  ? 


244  THE   MICROSCOPE. 


ined  with  the  same  magnifying  power,  namely,  from  one 
hundred  to  six  hundred  diameters.  Vegetable  hairs  or 
down  are  constantly  floating  in  air  and  water.  These  are 
of  very  various  forms,  are  simple  or  grouped,  and  form 
very  interesting  objects  of  study.  They  are  readily  pro- 
cured from  the  epidermis  or  outer  membrane  of  the  leaves 
or  stems  of  plants,  by  section  with  a  delicate  knife. 

15.  The  tissues  of  plants,  epidermis,  ducts,  and  woody 
fibres   are  constantly  found   in  "microscopic  preparations. 
They   may   be    studied   in   delicate    sections   made   with 
a  sharp  knife,  or  by  tearing  vegetable  tissues  apart  with 
needles.      The    down    of    moths,   the   hairs   of    difie rent- 
animals,  the  fibres  of   paper,  the  most   common  animal- 
cules   in   water,  the  dust  of   shelves,  and   generally  the 
structures  found   in  all  vegetable  and  animal  substances 
by  which  we  are  surrounded,  should  be  studied  as  a  pre- 
liminary to  any  special   line  of  microscopical   investiga- 
tion. 

16.  The  Study  of  Human  Tissues. — When  this  has 
been  done  and  familiarity  with  the  use  of  the  instrument 
has  been  obtained,  proceed  to  the  study  of  the  human 
body,  for  human  physiology  is  our  subject.     If  the  end  of 
the  finger  be  pricked  with  a  pin,  a  drop  of  blood  may  be 
procured  for  examination.     Place  this  on  one  of  the  glass 
slides,  cover  it  with  a  thin  piece  of  glass,  press  down  the 
cover  so  as  to  make  a  thin  layer,  and  then  examine  with 
the  magnifying  power  just  mentioned.     Do  not  add  water, 
for  that  will  cause  the  blood  corpuscles  to  disappear.     If 
the  drop  of  blood  is  placed  under  the  microscope  at  once 
after  being  drawn  from  the  finger,  most  interesting  phe- 
nomena will  be  observed.     The  red  corpuscles  will  be  seen 
to  arrange  themselves  in  rows,  like  piles  of  coin,  while  the 
blood  is  coagulating.     The  spherical,  white  corpuscles  will 


15.  Directions  for  examining  various  tissues?     Down  of  moths,  and  other 
structures  ? 

1 6.  Directions  for  examining  a  drop  of  blood  ? 


THE   MICROSCOPE.  245 


be  left  out  of  the  rows  of  red  disks,  and,  if  the  highest 
power  be  used,  will  be  seen  to  change  their  shape  con- 
stantly. 

17.  If  you  scrape  with  a  dull  knife  the  inside  of  the 
cheek,  the  flattened  scales  of  "  pavement  epithelium,"  or 
of  the  insensible  covering  which,  analogous  to  the  scarf- 
skin  on  the  outer  surface  of  the  body,  lines  the  cavities  of 
its  interior,  may  be  readily  studied.    They  have  the  appear- 
ance of  transparent   tiles,  each  enclosing  a  round  or  oval 
body,  called    its  nucleus.      Dandruff   and    the  scrapings 
from  the  skin  of  the  body  are  composed  of  scales  like 
those  of  the  mouth,  but  they  differ  somewhat  in  being 
hardened  by  horny  matter,  and   in  having  a  very  faint 
central  body  or  nucleus. 

18.  The  Tissues  of  the  Inferior  Animals. —  The 
warm-blooded  animals  do  not  differ  in  the  tissues,  or  mi- 
croscopic structures,  that  compose  them,  but  only  in   the 
amount  and  arrangement  of  these  tissues.     Milne  Edwards 
says  these  tissues  "  do  not  differ  much  in  different  animals, 
but  their  mode  of  association  varies;  and  it  is  chiefly  by 
reason  of  the  differences  in  the  combination  of  these  asso- 
ciations in  various  degrees,  that  each  species  possesses  the 
anatomical  properties  and  characters  which  are  peculiar 
to  it." 

19.  Hence  the  butcher's  stall  will  furnish  all  the  mate- 
rials for  the  study  of  the  microscopic  tissues.     The  struc- 
ture of  the  heart,  lungs,  liver,  brain,  and  muscle  may  all 
be  studied,  and  well  studied,  by  using  minute  pieces  of 
the  flesh  of  the  lower  animals,  especially  of  the  quadru- 
peds.    Such  portions  of  these  animals  as  are  not  exposed 
for  sale  can  be  readily  obtained  by  order  from  the  slaugh- 
ter-house.     To   examine   with   the   powers   of  which   we 
have  been  speaking,  it  is  only  necessary  to  cut  off  exceed- 

1  7.  Examination  of  the  scales  of  the  mouth  ?    Dandruff  ? 

18.  In  what,  as  respect*  the  tissues,  do  the  warm  blooded  animals  differ? 
Statement  of  Milne  Edwards  ? 

19.  How  to  procure  materials  for  the  study  of  the  tissues  of  man  ? 


246  THE   MICROSCOPE. 

ingly  small  pieces,  tear  them  apart  with  needles,  or  make 
very  delicate  sections  with  a  sharp  knife. 

20.  Incentives  to  Study. — A  complete  knowledge  of 
all  minute  structures  is  not  to  be  expected  at  once,  for  you 
are  here  introduced  into  a  new  realm  of  Nature,  a  world 
of  little  things  as  vast,  as  wonderful,  and  as  carefully  con- 
structed as  the  starry  firmament, — that   other  realm  of 
grand  objects  which  the  astronomer  nightly  scans  with  the 
telescope.     It  will  not  appear  singular,  therefore,  if,  at  first, 
you  feel  strange  and  awkward  in  this  new  creation.    With  a 
little  perseverance,  however,  and  with  the  attention  directed 
toward  simple  objects  at  the  outset,  it  will  not  be  long  be- 
fore an  increasing  experience  will  engender  confidence. 

21.  If  to  all  this  there  be  added  an  enthusiastic  study  of 
the  standard  authorities  on  the  subject,  the  rate  of  progress 
will  be  by  so  much  the  more  rapid.     As  compared  with 
similar  studies,  few  possess  more  interest  than  microscopy, 
and  to  the  one  who  pursues  it  with  fondness,  it  constantly 
affords  sources  of  pleasure  and  agreeable  surprises ;  and  in 
the  end,  often  leads  to  new  and  valuable  additions  to  the 
sum  of  human  knowledge.     The  depths  which  the  micro- 
scope is  employed  to  fathom  are  no  more  completely  known, 
than  are  the  heights  above  us  explored  and  comprehended 
by  the  astronomer. 


QUESTIONS  FOR  TOPICAL  REVIEW. 
State  what  you  can  on  the  following  subjects: 

\ .  Voice  and  speech 227,  228  ;  8.  Necessity  of  the  microscope  ...  236 

2.  The  or<;an  of  the  voice 2-28,  229  !     9.  Convex  lenses :>:J>r>,  237 

3.  The  vocal  cords 230.  231  ,   10.  Kinds  of  microscope 2:>7.  23S 

4.  The  production  of  the  voice. 232.  233  ;   11.  Choosinsr  a  microscope 23'.).  242 

5.  The  varieties  of  voice 233,  234  \   12.  Preliminary  studies 243,  244 

6.  Ventriloquism 235  \  13.  The  study  of  hnman  tissues 244 

7.  The  law  of  the  tissues 236  I  14.  The  study  of  the  inferior  animals  215 


APPENDIX. 


POISONS  AND  THEIR  ANTIDOTES. 

ACCIDENTS  from  poisoning  are  of  such  frequent  occurrence,  thai 
every  one  should  be  able  to  administer  the  more  common  antidotes, 
until  the  services  of  a  physician  can  be  obtained.  As  many  poisons 
bear  a  close  resemblance  to  articles  in  common  use,  no  dangerous 
substance  should  be  brought  into  the  household  without  having  the 
word  poison  plainly  written  or  printed  on  the  label ;  and  any  pack- 
age, box,  or  vial,  without  a  label,  should  be  at  once  destroyed,  if  the 
contents  are  not  positively  known. 

When  a  healthy  person  is  taken  severely  and  suddenly  ill  soon 
after  some  substance  has  been  swallowed,  we  may  suspect  that  he  has 
been  poisoned.  In  all  cases  where  poison  has  been  taken  into  the 
stomach,  it  should  be  quickly  and  thoroughly  evacuated  by  some 
active  emetic,  which  can  be  speedily  obtained  This  may  be  accom- 
plished by  drinking  a  tumblerful  of  warm  water,  containing  either  a 
tablespoonful  of  powdered  mustard  or  of"  common  salt,  or  two  tea- 
spoonfuls  of  powdered  alum  in  two  tablespoonfuls  of  syrup.  When 
vomiting  has  already  taken  place,  it  should  be  maintained  by  copious 
draughts  of  warm  water  or  mucilaginous  drinks,  such  as  gum-water 
or  flaxseed  tea,  and  tickling  the  throat  with  the  finger  until  there  is 
reason  to  believe  that  all  the  poisonous  substance  has  been  expelled 
from  the  stomach. 

The  following  list  embraces  only  the  more  common  poisons,  to 
getker  with  such  antidotes  as  are  usually  at  hand,  to  be  used  until 
the  physician  arrives. 

POISONS. 

Acids. — Hydrochloric  acid;  muriatic  acid  (spirits  of  salt);  nitric 
acid  (aqua  fortis) ;  sulphuric  acid  (oil  of  vitriol). 

ANTIDOTE. — An  antidote  should  be  given  at  once  to  neutralize  the 
acid.  Strong  soapsuds  is  an  efficient  remedy,  and  can  always  be 
obtained.  It  should  be  followed  by  copious  draughts  of  warm  water 
or  flaxseed  tea.  Chalk,  magnesia,  soda  or  saleraUis (with  water)' or 


248  APPENDIX. 


lime-water,  are  the  best  remedies.    When  sulphuric  acid  has  been 
taken,  water  should  be  given  sparingly,  because,  when  water  unites 
with  this  acid,  intense  heat  is  produced. 
Oxalic  acid. 

ANTIDOTE. — Oxalic  acid  resembles  Epsom  salts  in  appearance,  and 
may  easily  be  mistaken  for  it  The  antidotes  are  magnesia,  or  chalk 
mixed  with  water. 

Prussia  Acid;  oil  of  bitter  almonds  ;  laurel  water;  cyanide  of  potas- 
sium, (used  in  electrotyping). 

ANTIDOTE. — Cold  douche  to  the  spine.  Chlorine  water,  or  water 
of  ammonia  largely  diluted,  should  be  given,  and  the  vapor  arising 
from  them  may  be  inhaled. 

Alkalies  and  their  Salts. — AMMONIA  (hartshorn),  liquor  or  water 
of  ammonia.  POTASSA: — caustic  potash,  strong  ley,  carbonate  of  potassa 
(pearlash),  nitrate  of  potassa  (saltpetre). 

ANTIDOTE. — Give   the  vegetable  acids  diluted,  as  weak  vinegar, 
acetic,  citric,  or  tartaric  acids  dissolved  in  water.  Castor  oil,  linseed  oil, 
and  sweet  oil  may  also  be  used ;  they  form  soaps  when  mixed  with  the 
free  alkalies,  which  they  thus  render  harmless.   The  poisonous  effects 
of  saltpetre  must  be   counteracted  by  taking  mucilaginous  drinks 
freely,  so  as  to  produce  vomiting. 
Alcohol.. — Brandy,  wine  ;  all  spirituous  liquors. 
ANTIDOTE. — Give  as  an  emetic  ground  mustard  or  tartar  emetic.  If 
the  patient  cannot  swallow,  introduce  a  stomach  purnp ;  pour  cold 
water  on  the  head. 

Gases. — Chlorine,  carbonic  acid  gas,  carbonic  oxide,  fumes  of  burning 
'.haicoal,  sulphuretted  hydrogen,  illuminating  or  coal-gas. 

ANTIDOTE. — For  poisoning  by  chlorine,  inhale,  cautiously,  ammonia 
(hartshorn).    For  the  other  gases,  cold  water  should  be  poured  upon 
the  head,  and  stimulants  cautiously  administered  ;  artificial  icspira- 
tion.    (See  Marshall  Hall's  Ready  Method,  page  250.) 
Metals. — Antimony,  tartar  emetic,  wine  of  antimony,  etc. 
ANTIDOTE. — If  vomiting  has  not  occurred,  it  should  be  produced  by 
tickling  the  throat  with  the  finger  or  a  feather,  and  the  abundant  use 
Df  warm  water.    Astringent  infusions,  such  as  common  tea,  oak  bark, 
and  solution  of  tannin,  act  as  antidotes. 

Arsenic. —  White  arsenic,  FowUr's  solution,  fly-powder,  cobalt,  Paris 
green,  etc. 

ANTIDOTE. — Produce  vomiting  at  once  with  a  tablespoonful  or  two 
of  powdered  mustard  in  a  glass  of  warm  water,  or  with  ipecac.  The 
antidote  is  hydrated  peroxide  of  iron.  If  Fowler's  solution  has  been 
taken,  lime-water  must  be  given. 


APPENDIX.  249 


Copper. — Acetate  of  copper  (verdigris),  sulpliate  of  copper  (blue 
vitriol),  food  cooked  in  dirty  copper  vessels,  or  pickles  made  green 
by  copper. 

ANTIDOTE. — Milk  or  white  of  eggs,  with  mucilaginous  drinks  (flax 
seed  tea,  etc.),  should  be  freely  given. 

Iron.—Sulpliate  of  iron  (copperas),  etc. 

AJNTIDOTE. — Carbonate  of  soda  in  some,  mucilaginous  drink,  or  in 
water,  is  an  excellent  antidote. 

Lead. — Acetate  of  lesid  (sugar  of  lead;,  carbonate  of  lead  (white 
lead),  water  kept  in  Deaden  pipes  or  vessels,  food  cooked  in  vessels 
glazed  with  lead. 

ANTIDOTE. — Induce  vomiting  with  ground  mustard  or  common 
salt  in  warm  water.  The  antidote  for  soluble  preparations  of  lead  is 
Epsom  salts;  for  the  insoluble  forms,  sulphuric  acid  largely  diluted. 

Mercury. — Bichloride  of  mercury  (corrosive  sublimate),  ammoniated 
mercury  (white  precipitate),  red  oxide  of  mercury  (red  precipitate),  red 
sulphuret  of  mercury  (vermilion). 

ANTIDOTE. — The  white  of  eggs,  or  wheat  flour  beaten  up  with 
water  and  milk,  are  the  best  antidotes. 

Silver. ^— Nitrate  of  silver  (lunar  caustic). 

ANTIDOTE. — Give  a  teaspoonful  of  common  salt  in  a  tumbler  of 
water.  It  decomposes  the  salts  of  silver  and  destroys  their  activity. 

Zinc. — Sulphate  of  zinc,  etc.  (white  vitriol). 

ANTIDOTE. — The  vomiting  may  be  relieved  by  copious  draughts 
of  warm  water.  The  antidote  is  carbonate  of  soda  administered  in 
water. 

Narcotic  Poisons. — Opium  (laudanum,  paregoric,  salts  of  mor- 
phia, Godfrey's  cordial,  Dalby's  carminative,  soothing  syrup,  cholera 
mixtures),  aconite,  belladonna,  hemlock,  stramonium,  digitalis,  tobacco, 
hyosciamus,  nux  wmica,  strychnine. 

ANTIDOTE. — Evacuate  the  stomach  by  the  most  active  emetics,  as 
mustard,  alum,  or  sulphate  of  zinc.  The  patient  should  be  kept  in 
motion,  and  cold  water  dashed  on  the  head  and  shoulders.  Strong 
coffee  must  be  given.  The  physician  will  use  the  stomach  pump  and 
electricity.  In  poisoning  by  nux  vomica  or  strychnine,  etc.,  chloro- 
form or  ether  should  be  inhaled  to  quiet  the  spasms. 

Irritant  Vegetable  Poisons. — Croton  oil,  oil  of  samne,  poke,  oil  of 
tansy,  etc. 

ANTIDOTE — If  vomiting  has  taken  place,  it  may  be  rendered  easier 
by  copious  draughts  of  warm  water.  But  if  symptoms  of  insensibility 
have  come  on  without  vomiting,  it  ought  to  be  immediately  excited  b> 
ground  mustard  mixed  with  warm  water,  or  some  other  active  emo!;r 

11* 


250  APPENDIX. 


and  after  its  operation  an  active  purgative  should  be  given.  Aftei 
evacuating  as  much  of  the  poison  as  possible,  strong  coffee  or  vinegar 
and  water  may  be  given  with  advantage. 

Poisonous  Fish. — Conger  eel,  musseU,  crabs,  etc. 

ANTIDOTE.— Evacuate,  as  soon  as  possible,  the  contents  of  the  stom- 
ach and  bowels  by  emetics  (ground  mustard  mixed  with  warm  water 
or  powdered  alum),  and  castor  oil,  drinking  freely  at  the  same  time 
of  vinegar  and  water.  Ether,  with  a  few  drops  of  laudanum  mixed 
with  sugar  and  water,  may  afterward  be  taken  freely. 

Poisonous  Serpents. — ANTIDOTE. — A  ligature  or  handkerchief 
should  be  applied  moderately  tight  above  the  bite,  and  a  cupping-glass 
over  the  wound.  The  patient  should  drink  freely  of  alcoholic  stim- 
ulants containing  a  small  quantity  of  ammonia.  The  physician  may 
inject  ammonia  into  the  veins. 

Poisonous  Insects. — Stings  of  scorpion,  hornet,  wasp,  bee,  etc. 

ANTIDOTE. — A  piece  of  rag  moistened  with  a  solution  of  carbolic 
acid  may  be  kept  on  the  affected  part  until  the  pain  is  relieved  ;  and 
a  few  drops  of  carbolic  acid  may  be  given  frequently  in  a  little 
water.  The  sting  may  be  removed  by  making  strong  pressure 
around  it  with  the  barrel  of  a  small  watch-key. 


DROWNING. 

MARSHALL  HALL'S  "  READY  METHOD"  of  treatment  in  asphyxia 
from  drowning,  chloroform,  coal  gas,  etc. 

1st.  Treat  the  patient  instantly  on  the  spot,  in  the  open  air,  freely 
exposing  the  face,  neck,  and  chest  to  the  breeze,  except  in  severe 
weather. 

2d.  In  order  to  clear  ike  throat,  place  the  patient  gently  on  the  face, 
with  one  wrist  under  the  forehead,  that  all  fluid,  and  the  tongue  itself, 
may  fall  forward,  and  leave  the  entrance  into  the  windpipe  free. 

3d.  To  excite  respiration,  turn  the  patient  slightly  on  his  side,  and 
apply  some  irritating  or  stimulating  agent  to  the  nostrils,  as  vera 
trine^  dilute  ammonia,  etc. 

4th.  Make  the  face  warm  by  brisk  friction ;  then  dash  cold  water 
upon  it. 

5th.  If  not  successful,  lose  no  time ;  but,  to  imitate  respiration, 
place  the  patient  on  his  face,  and  turn  the  body  gently,  but  completely 
on  iJieside,  and  a  little  beyond;  then  again  on  the  face,  and  so  on,  al- 
ternately. Repeat  these  movements,  deliberately  and  perseveringly. 


APPENDIX.  25] 


•fifteen  times  only  in  a  minute.  (When  the  patient  lies  on  the  thorax, 
this  cavity  is  compressed  by  the  weight  of  the  body,  and  ezpiratiOD 
takes  place.  When  he  is  turned  on  the  side,  this  pressure  is  removed, 
and  t/ispiration  occurs.) 

6th.  When  the  prone  position  is  resumed,  make  a  uniform  and 
efficient  pressure  along  the  spine,  removing  the  pressure  immediately, 
before  rotation  on  the  side.  (The  pressure  augments  the  expiration  • 
the  rotation  commences  z'ftspiration.)  Continue  these  measures. 

7th.  Rub  the  limbs  upward,  with  firm  pressure  and  with  energy. 
(The  object  being  to  aid  the  return  of  venous  blood  to  the  heart.) 

8th.  Substitute  for  'the  patient's  wet  clothing,  if  possible,  such 
other  covering  as  can  be  instantly  procured,  each  bystander  sup- 
plying a  coat  or  cloak,  etc.  Meantime,  and  from  time  to  time,  to 
excite  inspiration,  let  the  surface  of  the  body  be  slapped  briskly  with 
the  hand. 

9th.  Rub  the  body  briskly  till  it  is  dry  and  warm,  then  dash  fold 
water  upon  it,  and  repeat  the  rubbing. 

Avoid  the  immediate  removal  of  the  patient,  as  it  involves  a 
dangerous  loss  of  time — also,  the  use  of  bellows,  or  any  forcing  instru- 
ment ;  also,  the  warm  bath,  and  all  rough  treatment. 


GLOSSARY. 


AB-DO'MEN  (Latin  abdo,  to  conceal).  The  largest  cavity  of  the  bouy 
containing  the  liver,  stomach,  intestines,  etc.;  the  belly. 

AB-SOR'BENTS  (L.  db  and  sorbeo,  to  suck  up).  The  vessels  which  take 
part  in  the  process  of  absorption. 

AB-SORP'TION.  The  process  of  sucking  up  fluids  by  means  of  an 
animal  membrane. 

AC-COM-MO-DA'TION  of  the  Eye.  The  alteration  in  the  shape  of  the 
crystalline  lens,  which  accommodates  or  adjusts  the  eye  for  near 
and  remote  vision. 

AC'ID,  LACTIC  (L.  lac,  milk).  The  acid  ingredient  of  sour  milk ;  the 
gastric  juice  also  contains  it. 

AL-BU'MEN,  or  Albumin  (L.  albus,  white).  An  animal  substance  re- 
sembling white  of  egg. 

AL-BU'MI-NOSE  (from  albumen).  A  soluble  animal  substance  pro- 
duced in  the  stomach  by  the  digestion  of  the  albuminoid  sub- 
stances. 

AL-BU'MIX-OID  substances.  A  class  of  proximate  principles  resembling 
albumen ;  they  may  be  derived  from  either  the  animal  or  vegetable 
kingdoms. 

AL'I-MENT  (L.  alo,  to  nourish).  That  which  affords  nourishment ; 
food. 

AL-I-MENT'A-BY  CA-NAL  (from  aliment).  A  long  tube  in  which  the 
food  is  digested,  or  prepared  for  reception  into  the  system. 

AN-^ES-THET'ICS  (Greek,  ar,  an,  without,  cdtiSijtita,  aistliesia,  feel 
ing). — Those  medicinal  agents  which  prevent  the  feeling  of  pain, 
such  as  chloroform,  laughing-gas,  etc. 

AN-I-MAI/CULE  (L.  animal'culum,  a  small  animal).  Applied  to  an- 
imals which  can  only  be  seen  with  the  aid  of  the  microscope.  Ani- 
malculum  (plural,  animalcula)  is  used  with  the  same  meaning. 

A-OR'TA  (Gr.  dopreotiai,  aorteomai,  to  be  lifted  up).  The  largest 
artery  of  the  body,  and  main  trunk  of  all  the  arteries.  It  arises  from 
the  left  ventricle  of  the  heart.  The  name  was  first  applied  to  the 
two  large  branches  of  the  trachea,  which  appear  to  be  lifted  up  by 
the  heart. 


GLOSSARY. 


A'QUE-OUS  HUMOR  (L.  aqua,  water).  A  few  drops  of  watery  color- 
less fluid  occupying  the  space  between  the  cornea  and  crystalline 
lens. 

A-RACH'NOID  MEM'BRANE  (Gr.  ctpaxTT/,  arachne,  a  cobweb,  and 
siSoS,  eidos,  like).  An  extremely  thin  covering  of  the  brain  and 
spinal  cord.  It  lies  between  the  dura  mater  and  the  pia  mater. 

A.R'BOR  VI'T^E  (L.).  Literally,  "the  tree  of  life;"  a  name  given  to  the 
peculiar  appearance  presented  by  a  section  of  the  cerebellum. 

AR'TER-Y  (Gr.  cirip,  aer,  air,  and  Tijpsiv,  terein,  to  contain).  A 
vessel  by  which  blood  is  conveyed  away  from  the  heart.  It  was 
supposed  by  the  ancients  to  contain  air ;  hence  the  name. 

AR-TIC-U-LA'TION  (L.  articulo,  to  form  a  joint).  The  more  or  less 
movable  union  of  bones,  etc. ;  a  joint. 

A-RYT'E-NOID  CAR'TI-LA-GES  (Gr.  apvroara,  arutaina,  a  pitcher). 
Two  small  cartilages  of  the  larynx,  resembling  the  mouth  of  a 
pitcher. 

A  S-SIM-I-LA'TION  (L.  ad,  to,  and  similis,  like).  The  conversion  of  food 
into  living  tissue. 

AU-DI'TION  (L.  audio,  to  hear).     The  act  of  hearing  sounds. 

AU'DI-TO-RY  NERVE.  One  of  the  cranial  nerves;  it  is  the  special 
nerve  of  hearing. 

AU'RI-CLE  (L.  auris,  the  ear).    A  cavity  of  the  heart. 

BAR'I-TONE  (Gr.  fiapvt,  barus,  heavy,  and  roVo?,  tonos,  tone).  A 
variety  of  male  voice  between  the  bass  and  tenor. 

BEL-LA-DON'NA  (It.  beautiful  lady).  A  vegetable  narcotic  poison.  It 
has  the  property  of  enlarging  the  pupil,  and  thus  increasing  the 
brilliancy  of  the  eye ;  so  called  from  its  use  by  Italian  ladies. 

BI-CUS'PID  (L.  U,  two,  and  cuspis,  prominence).  The  name  of  the 
fourth  and  fifth  teeth  on  each  side  of  the  jaw ;  possessing  two  prom- 
inences. 

BILE.  The  gall,  or  peculiar  secretion  of  the  liver ;  a  viscid,  yellowish 
fluid,  and  very  bitter  to  the  taste. 

BRONCH'I  (Gr.  fipoyxoS,  bronkos,  the  windpipe).  The  two  first 
divisions  or  branches  of  the  trachea ;  one  enters  each  lung. 

BRONCH'I- AL  TUBES.  The  smaller  branches  of  the  trachea  within 
the  substance  of  the  lungs,  terminating  in  the  air-cells. 

BRONCH-I'TIS  (from  bronchia,  and  itis,  a  suffix  signifying  inflamma- 
tion). An  inflammation  of  the  larger  bronchial  tubes ;  a  "  cold" 
affecting  the  lungs. 

CAL-CA'RE-OUS  (L.  calx,  lime).    Containing  lime. 

CA-NAL'  (L.).    In  the  body,  any  tube  or  passage. 

CA-NINE'  (L.  canis,  a  dog).    Name  given  to  the  third  tooth  on  each 


254  GLOSSARY. 


side  of  the  jaw ;  in  the  upper  jaw  it  is  also  known  as  the  eye-tootn: 
pointed  like  the  tusks  of  a  dog. 

CAP'IL-LA-RY  (L.  capil'lus,  a  hair,  capiUa'rix  hair-like).  The  name  of 
the  extremely  minute  blood-vessels  which  connect  the  arteries  with 
the  veins. 

CAR'BON  DIOX-IDE  (CO»).     Chemical  name  for  carbonic  acid  gas. 

CAR-BON' ic  A-CID.  The  gas  which  is  present  in  the  air  expired  from 
the  lungs ;  a  waste  product  of  the  animal  kingdom,  and  a  food  of 
the  vegetable  kingdom. 

CAR'DI-AC  (Gr.  xapdia,  cardia,  the  heart).  The  cardiac  orifice  of 
the  stomach  is  the  upper  one,  and  is  near  the  heart ;  hence  its 
name. 

CAR-NIV'O-ROUS  (L. ca'ro,  flesh,  and  w'ro,  to  devour).  Subsisting 
upon  flesh. 

CA-ROT'ID  AR-TE-RT.  The  large  artery  of  the  neck,  supplying  the 
head  and  brain. 

CAR'TI-LAGE.  A  solid  but  flexible  material,  forming  a  part  of  the 
joints,  air-passages,  nostrils,  etc. ;  gristle. 

CA'SE-INE  (L.  ca'seus,  cheese).  The  albuminoid  substance  of  milk ; 
it  forms  the  basis  of  cheese. 

CER-E-BEL'LUM  (diminutive  for  cer'ebrum,  the  brain).  The  little  brain, 
situated  beneath  the  posterior  third  of  the  cerebrum. 

CER'E-BRUM  (L.).  The  brain  proper,  occupying  the  entire  upper  por- 
tion of  the  skull.  It  is  nearly  divided  into  two  equal  parts,  called 
"  hemispheres,"  by  a  cleft  extending  from  before  backward. 

CHO'ROID  (Gr.  xopiov,  chorion,  a  membrane  or  covering).  The  mid- 
dle tunic  or  coat  of  the  eyeball. 

CHYLE  (Gr.  *vA.o'£,  cliulos,  juice).  The  milk-like  fluid  formed  by  the 
digestion  of  fatty  articles  of  food  in  the  intestines. 

CHYME  (Gr.  j^v/noS,  ckumos,  juice).  The  pulpy  liquid  formed  by 
digestion  within  the  stomach. 

CIL'I-A  (pi.  of  til'i-um,  an  eyelash).  Minute,  vibratile,  hair -like  pro- 
cesses found  upon  the  cells  of  the  air-passages,  and  other  parts  that 
are  habitually  moist. 

CIR-CU-LA'TION  (L.  cir'culus,  a  ring).  The  circuit,  or  course  of  the 
blood  through  the  blood-vessels  of  the  body,  from  the  heart  to  the 
arteries,  through  the  capillaries  into  the  veins,  and  from  the  veins 
back  to  the  heart. 

CO-AQ-U-LA'TION  (L.  coatfulo,  to  curdle).  Applied  to  the  process  by 
which  the  blood  clots  or  solidifies. 

COCH'LE-A  (L.  coch'lea,  a  snail-shellV  The  spiral  cavity  of  the  in- 
ternal ear. 


GLOSSARY.  255 

CONCH' A  (Gr.  noyxrj,  konche,  a  mussel-shell).  The  external  shell- 
sliap  jd  portion  of  the  external  ear. 

OON-JTTNC-TI'VA  (L.  con  and  jurigo,  to  join  together).  A  thin  layer 
of  mucous  membrane  which  lines  the  eyelids  and  covers  the  front 
of  the  eyeball ;  thus  joining  the  latter  to  the  lids. 

OON-TRAC-TIL'I-TY  (L.  con  and  tra'ho,  to  draw  together).  The  prop- 
erty of  a  muscle  which  enables  it  to  contract,  or  draw  its  extrem- 
ities closer  together. 

OON-VO-VQ'TIONS  (L.  con  and  vol'vo,  to  roll  together).  The  tortuous 
foldings  of  the  extenal  surface  of  the  brain. 

CON-VUJ/SION  (L.  convel'lo,  to  pull  together).  A  more  or  less  violent 
agitation  of  the  limbs  or  body. 

COR'NE-A  (L.  cor'nu,  a  horn).  The  transparent,  horn-like  substance 
which  covers  the  anterior  fifth  of  the  eyeball. 

COR'FUS-CLES,  BLOOD  (L.  dim.  of  cor' pus,  a  body).  The  small  bicon- 
cave disks  which  give  to  the  blood  its  red  color ;  the  white  cor- 
puscles are  globular  and  larger. 

COS-MET'IC  (Gr.  nodjusoa,  kosmeo,  to  adorn).  Beautifying;  applied 
to  articles  which  are  supposed  to  increase  the  beauty  of  the 
skin,  etc. 

CRA'NI-AL  (L.  cra'nium,  the  skull).  Pertaining  to  the  skull.  The 
nerves  which  arise  from  the  brain  are  called  cranial  nerves. 

CKI'COID  (Gr.  KpixoS,  kri'kos,  a  ring).  A  cartilage  of  the  larynx, 
resembling  a  seal-ring  in  shape. 

CRYS'TAL-LINE  LENS  (L.  crystal'lum,  a  crystal).  One  of  the  so-called 
humors  of  the  eye ;  a  double  convex  body  situated  in  the  front  part 
of  the  eyeball. 

CU'TI-CLE  (L.  dim.  ofcu'tis,  the  skin).  The  scarf-skin  ;  also  called 
the  epider'mis. 

CU'TIS  (Gr.  <5nvro$%  skutos,  a  skin  or  hide).  The  true  skin,  lying 
beneath  the  cuticle ;  also  called  the  der'ma. 

DE-CUS-SA'TION  (L.  decus'sis,  the  Roman  numeral  ten,  X).  A  re- 
ciprocal crossing  of  fibres  from  side  to  side. 

DI'A-PHRAGM  (Gr.  dtacppdddoo,  diaplirasso,  to  divide  by  a  partition). 
A  large,  thin  muscle  which  separates  the  cavity  of  the  chest  from 
the  abdomen ;  a  muscle  of  respiration. 

DIF-FUS'ION  OF  GASES.  The  power  of  gases  to  become  intimately 
mingled,  without  reference  to  the  force  of  gravity. 

DUCT  (L.  du'co,  to  lead).  A  narrow  tube ;  the  flwracic  duct  is  the 
main  trunk  of  the  absorbent  vessels. 

DU-O-DE'NUM  (L.  duode'ni,  twelve).  The  first  division  of  the  small 
intestines,  about  twelve  fingers-breadth  long. 


256  GLOSSARY. 


DU'RA  MA'TER  (L.).  Literally,  the  hard  mother ;  the  tough  membrane 
which  envelops  the  brain. 

UYS-PEP'SI-A  (Gr.  dvS,  dus,  difficult,  an&iteitrGOypep'to,  to  digest).  Dif- 
ficult or  painful  digestion  ;  a  disordered  condition  of  the  stomach. 

E-MUI/SION  (L.  emul'geo,  to  milk).  Oil  in  a  finely  divided  state  sus- 
pended in  water. 

EN-AM'EL  (Fr.  email).  The  dense  material  which  covers  the  crown 
of  the  tooth. 

EN'ER-GY,  Specific,  of  a  Nerve.  When  a  nerve  of  special  sense  is 
excited,  whatever  be  the  cause,  the  sensation  experienced  is  that 
peculiar  to  the  nerve ;  this  is  said  to  be  the  law  of  the  specific 
energy  of  the  nerves. 

EP-I-GLOT'TIS  (Gr.  £7ti,  epi,  upon,  and  yXoorriS,  glottis,  the  entrance 
to  the  windpipe).  A  leaf-shaped  piece  of  cartilage  which  covers 
the  top  of  the  larynx  during  the  act  of  swallowing. 

EX-CRE'TION  (L.  excer'no,  to  separate).  The  separation  from  the  blood 
of  the  waste  particles  of  the  body ;  also  the  materials  excreted. 

EX-PI-RA'TION  (L.  expi'ro,  to  breathe  out).  The  act  of  forcing  air  out 
of  the  lungs. 

EX-TEN'SION  (L.  ex,  out,  and  ten' do,  to  stretch).  The  act  of  restoring  a 
limb,  etc.,  to  its  natural  position  after  it  has  been  flexed,  or  bent ; 
the  opposite  of  Flexion. 

FE-NES'TRA  (L.).  Literally,  a  window ;  the  opening  between  the 
middle  and  internal  ear. 

FI'BRIN  (L.  fi'bra,  a  fibre).  An  albuminoid  substance  found  in  the 
blood;  in  coagulating  it  assumes  a  fibrous  form. 

FLEX' ION  (L.  flee' to,  to  bend).    The  act  of  bending  a  limb,  etc. 

FOL/LI-CLE  (L.  dim.  offol'lis,  a  bag).  A  little  pouch  or  depression  in  a 
membrane  ;  it  has  generally  a  secretory  function. 

FUN'GOUS  GROWTHS  (L.fun'gus,  a  mushroom).  A  low  grade  of  vege- 
table life. 

GAN'GLI-ON  (Gr.  yayyXiov,  ganglion,  a  knot).  A  knot-like  swell- 
ing in  the  course  of  a  nerve ;  a  smaller  nerve-centre. 

GAS'TRIC  (Gr.  yadrrfp,  gaster,  stomach).    Pertaining  to  the  stomach. 

GLAND  (L.  glans,  an  acorn).  An  organ  consisting  of  follicles  and 
ducts,  with  numerous  blood-vessels  interwoven ;  it  separates  some 
particular  fluid  from  the  blood. 

TLOS'SO-PHAR-YN-GE'AL  NERVE  (Gr.  yXooGGa,  glossa,  the  tongue,  and 
(pdpvyE,  pharunx,  the  throat).  The  nerve  of  taste  supplying  the 
posterior  third  of  the  tongue;  it  also  supplies  the  throat 

GLU'TEN  (L.).  Literally,  glue  :  the  glutinous  albuminoid  ingredient 
of  wheat. 


GLOSSARY.  257 


E   (L.  dim.  of  gra'num,  a  grain).    A  little  grain;  a  micro- 
scopic object. 

GUS-TA'TION  (L.  gus'to,  to  taste).     The  sense  of  taste. 
GUS'TA-TO-RY  NERVE.    The  nerve  of  taste  supplying  the  front  part 

of  the  tongue;  a  branch  of  the  "  fifth"  pair. 
ELEM'OR-RHAGE  (Gr.  ai/j.a,  hai'ma,  blood,  and  pijyrvjui,  regnumi, 

to  burst).    Bleeding,  or  the  loss  of  blood. 
HEM-I-PLE'GIA  (Gr.  ^//ztfuS,  hemisus,  half,  and  TrA^tftfoj,  pletso,    to 

strike).    Paralysis,  or  loss  of  power,  affecting  one  side  of  the  body. 
HEM'I-SPHERES  (Gr.  ticpoupa,  sphaira,  a  sphere).  Halt  a  sphere,  the 
-  lateral  halves  of  the  cerebrum,  or  brain  proper. 
HE-PAT' ic  (Gr.  r/ttap,  tiepar,  the  liver).    Pertaining  to  the  liver. 
HER-BIV'O-ROUS  (L.  lier'ba,  an  herb,  and  vo'ro  to  devour).     Applied 

to  animals  that  subsist  upon  vegetable  food. 
HU'MOR  (L.).   Moisture :  the  humors  are  transparent  contents  of  the 

eyeball. 
HY-DRO-PHO'BI-A  (Gr.  vdop,  hudor,  water,  and  fpofiea),  phobeo,  to 

fear).    A  disease  caused  by  the  bite  of  a  rabid  dog  or  other  animal. 

In  a  person  affected  with  it,  convulsions  are  occasioned  by  the  sight 

of  a  glittering  object,  like  water,  by  the  sound  of  running  water, 

and  by  almost  any  external  impression. 
HY'GI-ENE  (Gr.   vyi£ia,  huygieia,  health).    The  art  of  preserving 

health  and  preventing  disease. 
HY'PER-O-PI-A.    Abbreviated  from  HY'PER-MET-RO'PI-A  (Gr.  vnep, 

kupei\  beyond,  juerpov,  metron,  the  measure,  and  ooip,  ops,  the  eye). 

A  defect  of  vision  dependent  upon  a  too  short  eyeball ;  so  called 

because  the  rays  of  light  are  brought  to  a  focus  at  a  point  behind 

the  retina ;  the  true  "  far  sight." 
IN-CI'SOR  (L.  ind'do,  to  cut).    Applied  to  the  four  front  teeth  of  both 

jaws,  which  have  sharp  cutting  edges. 
IN'CTJS  (L).    An  anvil ;  the  name  of  one  of  the  bones  of  the  middle 

ear. 
IN-SAL-I-VA'TION  (L.  in,  and  salfva,  the  fluid  of  the  mouth).    The 

mingling  of  the  saliva  with  the  food  during  the  act  of  chewing. 
IN-SPI-RA'TION  (L.  t»,  and  spi'ro,  spira'tum,  to  breathe).    The  act  of 

drawing  in  the  breath. 
IN-TEG'U-MENT  (L.  t»,  and  te'go,  to  cover).   The  skin,  or  outer  covering 

of  the  body. 
IN-TES'TTNE  (L.  in'tus,  within).    The  part  of  the  alimentary  canal 

which  is  continuous  with  the  lower  end  of  the  stomach ;  also  called 

the  intestines,  or  the  bowels. 
['RIS  (L.  i'ris,  the  rainbow).     The  thin  muscular  ring  which  lies  be- 


258  GLOSSARY. 


tween  the  cornea  and  crystalline  lens,  and  which  gives  the  eye 

its  brown,  blue,  or  other  color. 
JU'GU-LAR  (L.ju'gulum,  the  throat).     The  name  of  the  large  veins 

which  run  along  the  front  of  the  neck. 
LAB'Y-RESTH  (Gr.  A.afivpir$o$,  labunn'thos,  a  building  with  many 

winding  passages).    The  very  tortuous  cavity  of  the  inner  ear, 

comprising  the  vestibule,  semicircular  canals,  and  the  cochlea. 
LACH'RY-MAL  APPARATUS  (L.  lach'ryma,  a  tear).    The  organs  for 

forming  and  conveying  away  the  tears. 
LAC'TE-ALS  (L.  lac,  lac'tis,  milk).    The  absorbent  vessels  of  the  small 

intestines ;  during  digestion  they  are  filled  with  chyle,  which  has 

a  milky  appearance. 
LA-RYN'GO-SCOPE    (Gr.  Hdpvy$9  larunx,  the  larynx,  and  tino-tea), 

skopeo,  to  look  at).    The  instrument  by  which  the  larynx  may  be 

examined  in  the  living  subject. 
LAR'YNX  (Gr.).    The  cartilaginous  tube  situated  at  the  top  of  the 

windpipe,  or  trachea ;  the  organ  of  the  voice. 

LENS  (L.).  Literally,  a  lentil ;  a  piece  of  transparent  glass  or  other  sub- 
stance so  shaped  as  either  to  converge  or  disperse  the  rays  of  light. 
I  jo  A-MENT  (L.  I? go,  to  bind).     A  strong,  fibrous  material  binding 

bones  or  other  solid  parts  together ;  it  is  especially  necessary  to 

give  strength  to  joints. 
LIG'A-TURE.    A  thread  of  silk  or  other  material  used  in  tying  around 

an  artery. 

LYMPH  (L.  lym'pha,  spring-water).     The  colorless,  watery  fluid  con- 
veyed by  the  lymphatic  vessels. 

LYM-PHAT'IC  VESSELS.    A  system  of  absorbent  vessels. 
MAL'LE-US  (L.).    Literally,  the  mallet;  one  of  the  small  bones  of  the 

middle  ear. 
MAR'ROW.    The  soft,  fatty  substance  contained  in  the  central  cavities 

of  the  bones :  the  spinal  marrow,  however,  is  composed  of  nervous 

tissue. 

MAS-TI-CA'TTON  (L.  mas'tico,  to  chew).    The  act  of  cutting  and  grind- 
ing the  food  to  pieces  by  means  of  the  teeth. 
ME-DUL'LA  OB-LON-GA'TA.    The  "  oblong  marrow,"  or  nervous  cord. 

which  is  continuous  with  the  spinal  cord  within  the  skull. 
MEM-BRA'NA  TYM'PAN-I  (L.).    Literally,  the  membrane  of  the  drum ; 

a  delicale  partition  separating  the  outer  from  the  middle  ear;  it  is 

sometimes  incorrectly  called  the  drum  of  the  ear. 
MEM'BRANE.    A  thin  layer  of  tissue  serving  to  cover  some  part  of 

the  body. 
MI'CRO-SCOPE  (Gr.  yutx/oo?,  mflf.rn*)  small,  and  ^H^TTSGOJ  skopeo^  to 


GLOSSARY.  259 


look  at).     An  optical  instrument  which  assists  in  the  examination 

of  minute  objects. 
MO'LAR  (L.  mo'la,  a  mill).     The  name  applied  to  the  three  back  teeth 

of  each  side  of  the  jaw ;  the  grinders,  or  mill-like  teeth. 
MO'TOR  (L.  mo'veo,  mo' turn,  to  move).     Causing  motion ;  the  name 

of  those  nerves  which  conduct  to  the  muscles  the  stimulus  which 

causes  them  to  contract. 

Mu'cous  MEM'BRANE.   The  thin  layer  of  tissue  which  covers  those  in- 
ternal cavities  or  passages  which  communicate  with  the  external  air. 
Mo'cus.     The  glairy  fluid  which  is  secreted  by  mucous  membranes, 

and  which  serves  to  keep  them  in  a  moist  condition. 
MY-O'PI-A  (Gr.  m'ao,  muo,  to  contract,  and  GOI{>,  ops,  the  eye).    A  de- 
fect of  vision  dependent  upon  an  eyeball  that  is  too  long,  rendering 

distant  objects  indistinct ;  near-sight. 
NA'SAL  (L.  na'sus,  the  nose).    Pertaining  to  the  nose ;    the  n(tsa> 

cavities  contain  the  distribution  of  the  special  nerve  of  smeil. 
NERVE  (Gr.  vevpor,  neuron,  a  cord  or  string).     A  glistening,  white 

cord  of  cylindrical  shape,  connecting  the  brain  or  spinal  cord  with 

some  other  organ  of  the  body. 
NERVE  CELL.    A  minute,  round  and  ashen-gray  eel1  umnd  in  the 

brain  and  other  nervous  centres. 
NERVE  FI'BRE.     An  exceedingly  slender  thread  of  nervous  tissue 

found  in  the  various  nervous  organs,  but  especially  in  the  nerves  ; 

it  is  of  a  white  color. 
NU-TRI'TION  (L.  nu'trio,  to  nourish).     The  processes  by  which  the 

nourishment  of  the  body  is  accomplished. 
(E-SOPH'A-GUS  (Gr.).    Literally,  that  which  carries  food.    The  tube 

leading  from  the  throat  to  the  stomach ;  the  gullet. 
O-LE-AG'I-NOUS  (L.  o'leum,  oil).    Of  the  nature  of  oil :  applied  to  aii 

important  group  of  food-principles — the  fats. 

OL-FAC'TO-RY  (L.  olfa'cio,  to  smell).    Pertaining  to  the  sense  of  smell. 
OPH-THAL'MO-SCOPE  (Gr.  o<p3o:/l//o?,  ophthalmos,  the  eye,  and  GKO~ 

item,  skopeo,  to  look  at).    An  instrument  devised  for  examining  the 

interior  of  the  globe  of  the  eye. 

OP'TIC  (Gr.  oTtTGOj  opto,  to  see).    Pertaining  to  the  sense  of  sight. 
OR'BIT  (L.  or'bis,  the  socket).    The  bony  socket  or  cavity  in  which 

the  eyeball  is  situated. 
OS'MOSE  (Gr.  aodjuoS,  osmos,  a  thrusting  or  impulsion).    The  process 

by  which  liquids  are  impelled  through  a  moist  membrane. 
OS'SE-OUS  (L.  os,  a  bone).    Consisting  of,  or  resembling  bone. 
PAL' ATE  (L.  pala'tum,  the  palate).     The  roof  of  the  mouth,  consisting 

of  the  hard  and  soft  palate. 


260  GLOSSARY. 


PAL'MAR.     Relating  to  the  palm  of  the  hand. 

PAN'ORE-AS  (Gr.  Ttat,  Karros,  pas,  pantos,  all,  and  xpsaS,  kreas, 
flesh).  A  long,  flat  gland  situated  near  the  stomach  ;  in  the  lower 
animals  the  analogous  organ  is  called  the  sweet-bread. 

PA-PIL'L^E  (L.  papil'la).  The  minute  prominences  in  which  termi- 
nate the  ultimate  fibres  of  the  nerves  of  touch  and  taste. 

PA-RAi/r-srs.  A  disease  of  the  nervous  system  marked  by  the  !;/»s 
of  sensation,  or  voluntary  motion,  or  both  ;  palsy. 

PAR-A-PI.E'GI-A  (Gr.  Ttapa.7fXrf(5(5Ga,  paraplesso,  to  strike  amiss).  A 
form  of  paralysis  affecting  the  lower  half  of  the  body. 

PA-TEL' LA  (L.  dim.  of  pat'ina,  a  pan).  The  knee-pan;  a  small 
bone. 

PEL'VIS  (L.).  Literally  a  basin  ;  the  bony  cavity  at  the  lower  part  of 
the  trunk. 

PEP'SIN  (Gr.  TteifcGo,  pepto,  to  digest).  The  organic  principle  of  the 
gastric  juice. 

PER-I-STAL'TIC  MOVE'MENTS  (Gr.  XEpttfrsAXco,  peristello,  to  contract). 
The  slow,  wave-like  movements  of  the  stomach  and  intestines. 

PER-I-TO-NE'UM  (Gr.  TtspireivGo,  penteino,  to  stretch  around).  The 
investing  membrane  of  the  stomach,  intestines,  and  other  abdom- 
inal organs. 

PER-SPI-RA'TTON  (L.  persptro,  to  breathe  through).  The  sweat,  or 
watery  exhalation  of  the  skin ;  when  visible,  it  is  called  sensible 
perspiration,  when  invisible,  it  is  called  insensible  perspiration. 

PE'TROUS  (Gr.  xsrpa,  petra,  a  rock).  The  name  of  the  hard  portion 
of  the  temporal  bone,  in  which  is  situated  the  drum  of  the  ear  and 
labyrinth. 

PHAR'YNX  (Gr.  cpdpvyk,  pJiarunx,  the  throat).  The  cavity  between 
the  back  of  the  mouth  and  gullet. 

PHYS-I-OL'CMSY  (Gr.  <pv<5i$,  phusis,  nature,  and  Ad^o?,  logos,  a  dis- 
course). The  science  of  the  functions  of  living,  organized  beings. 

PI'A  MA'TER  (L.).  Literally,  the  tender  mother;  the  innermost  of  the 
three  coverings  of  the  brain.  It  is  thin  and  delicate ;  hence  the 
name. 

PLEU'RA  (Gr.  nXEvpa,  a  rib).  A  membrane  covering  the  lung  and 
lining  the  chest.  There  is  one  for  each  lung. 

PLEU'RI-SY.    An  inflammation  affecting  the  pleura. 

PNEU-MO-GAS'TRIC  (Gr.  TCVEVJJ.&V,  pneumon,  the  lungs,  and  ya6Ti)pt 
gaster,  the  stomach).  The  name  of  a  nerve  distributed  to  the  lungs 
and  stomach ;  it  is  the  principal  nerve  of  respiration. 

PNEU-MO'NIA  (Gr.).  An  inflammation  affecting  the  air-cells  of  the 
lungs. 


GLOSSARY.  261 


PRES-BY-O'PI-A  (Gr.  TtpsdfiVs,  presbuS)  old,  and  GJI/>,  ops,  the  eye). 
A  defect  of  the  accommodation  of  the  eye,  caused  by  the  harden- 
ing of  the  crystalline  lens ;  the  "  far-sight"  of  adults  and  aged 
persons. 

PJIOC'ESS  (L.  proce'do,  proces'sus,  to  proceed,  to  go  forth).  Any  pro- 
jection from  a  surface.  Also,  a  method  of  performance ;  a  pro- 
cedure. 

PTY'A-LIN  (Gr.  itrvaXov,  ptualon,  saliva).  The  peculiar  organic 
ingredient  of  the  saliva. 

PUL'MO-NA-RY  (L.  pul'mo,  pulmo'nis,  the  lungs).  Pertaining  to  the 
lungs. 

PULSE  (L.  pel'lo,  pul'sum,  to  beat).  The  striking  of  an  artery  against 
the  finger,  occasioned  by  the  contraction  of  the  heart,  commonly 
felt  at  the,  wrist. 

PU'PIL  (L.  pupil'la).  The  central,  round  opening  in  the  iris,  through 
which  light  passes  into  the  depths  of  the  eye. 

PY-T>O'RUS  (Gr.  7tvha)p6's,  puloros,  a  gate-keeper).  The  lower  open- 
ing of  the  stomach,  at  the  beginning  of  the  small  intestine. 

RE'FLEX  ACTION.  An  involuntary  action  of  the  nervous  system,  by 
which  an  external  impression  conducted  by  a  sensory  nerve  is 
reflected,  or  converted  into  a  motor  impulse. 

RES-FI-RA'TION  (L.  res'piro,  to  breathe  frequently).  The  function 
of  breathing,  comprising  two  acts :  inspiration,  or  breathing  in,  and 
expiration,  or  breathing  out. 

HET'I-NA  (L.  re'te,  a  net).  The  innermost,  of  the  three  tunics  or  coats 
of  the  eyeball,  being  an  expansion  of  the  optic  nerve. 

SAC'CHA-RINE  (L.  sac'cliarum,  sugar).  Of  the  nature  of  sugar; 
applied  to  the  important  group  of  food  substances  which  embraces 
the  different  varieties  of  sugar,  starch,  and  gum. 

SA-LI'VA  (L.).  The  moisture  or  fluids  of  the  mouth,  secreted  by  the 
salivary  glands,  etc. 

SCLE-ROT'IC  (Gr.  tiKXrjpoS,  skleros,  hard).  The  tough,  fibrous  outer 
tunic  of  the  eyeball. 

SE-BA'CEOUS  (L.  sebum,  fat).  Resembling  fat ,  the  name  of  tnc  oily 
secretion  by  which  the  skin  is  kept  flexible  and  soft. 

SE-CRE'TION  (L.  secer'no,  secre'tum,  to  separate).  The  process  ol 
separating  from  the  blood  some  essential  important  fluid ;  which 
fluid  is  also  called  a  secretion. 

SEM-I-CIR'CU-LAR  CANALS.    A  portion  of  the  internal  ear. 

SEN-SA'TION.  The  perception  of  an  external  impression  by  the  ner- 
vous system ;  a  function  of  the  brain. 

SEN-SI-BIL'I-TY,  GENERAL.     The  power  possessed  by  nearly  aU  parts 


262  GLOSSARY. 


of  the  human  body  of  recognizing  the  presence  of  foreign  objects 
that  come  in  contact  with  them. 

SE'RUM  (L.).  The  watery  constituent  of  the  blood,  which  separates 
from  the  clot  during  the  process  of  coagulation. 

SKEL'E-TON  (Gr.).  The  bony  framework  of  an  animal,  the  different 
parts  of  which  are  maintained  in  their  proper  relative  positions. 

SPEC'TRO-SCOPE  (from  spec'trum  and  tino-neco,  scopeo,  to  examine  the 
spectrum).  An  instrument  employed  in  the  examination  of  the 
spectrum  of  the  sun  or  any  other  luminous  body. 

SPHYG'MO-GRAPH  (Gr.  GcpvynoS,  sphugmos,  the  pulse,  and  ypaqxa, 
grapl*),  to  write).  An  ingenious  instrument  by  means  of  which 
the  pulse  is  delineated  upon  paper. 

STA'PES  (L.).  Literally,  a  stirrup ;  one  of  the  small  bones  of  the  tym- 
panum, or  middle  ear,  resembling  somewhat  a  stirrup  hi  shape. 

SYM-PA-THET'IC  SYSTEM  OF  NERVES.  A  double  chain  of  nervous 
ganglia,  connected  together  by  numerous  small  nerves,  situated 
chiefly  in  front  of  and  on  each  side  of  the  spinal  column. 

SYN-O'VI-A  (Gr.  dvv,  sun,  and  coov,  oon,  resembling  an  egg).  The 
lubricating  fluid  of  joints,  so  called  because  it  resembles  the  white 
of  egg. 

SYS'TO-LE  (Gr.  6v tfrs'AAo?,  sustello,  to  contract).  The  contraction  of 
the  heart,  by  which  the  blood  is  expelled  from  that  organ. 

TAC'TILE   (L.  tac'tus,  touch).    Relating  to  the  sense  of  touch. 

TEM'PO-RAL  (L.  tem'pust  time,  and  tem'pora,  the  temples).  Pertain- 
ing to  the  temples ;  the  name  of  an  artery :  so  called,  because  the 
hail  begins  to  turn  white  with  age  in  that  portion  of  the  scalp. 

TEN'DON  (L.  ten'do,  to  stretch).  The  white,  fibrous  cord  or  band  by 
which  a  muscle  is  attached  to  a  bone ;  a  sinew. 

TET'A-NUS  (Gr.  retroo,  teino,  to  stretch).  A  disease  marked  by  per- 
sistent contractions  of  all  or  some  of  the  voluntary  muscles ; 
those  of  the  jaw  are  sometimes  solely  affecte^  the  disorder  is  then 
termed  locked-jaw. 

THO'RAX  (Gr.  Scopac,  thorax,  a  breastplate).  The  upper  cavity  of 
the  trunk  of  the  body,  containing  the  lungs,  heart,  etc. ;  the 
chest. 

THY'ROID  (Gr.  3vp£o'S,  thureos,  a  shield).  The  largest  of  the  carti- 
lages of  the  larynx ;  its  angular  projection  in  the  front  of  the  neck 
is  called  "  Adam's  apple." 

TRA'CIIE-A  (Gr.  rpaxvS,  trachus,  rough).  The  windpipe,  or  the 
largest  of  the  air-passages ;  composed  in  part  of  cartilaginous 
rings,  which  render  its  surface  rough  and  uneven. 

TKANS-FU'SION  (L.  tramfun'do.  to  pour  from  one  vessel  to  another). 


GLOSSARY.  203 


The  operation  of  injecting  blood  taken  from  one  person  into  the 
veins  of  another;  other  fluids  than  blood  are  sometimes  used. 

TJUCII-I'NA  SPI-RA'LIS.  (L.)  A  minute  species  of  parasite  or  worm, 
which  infests  the  flesh  of  the  hog,  and  which  may  be  introduced 
into  the  human  system  by  eating  pork  not  thoroughly  cooked. 

TYM'PA-NUM  (Gr.  TV/J.TCO.VOV,  tumpanon,  a  drum).  The  cavity  of 
the  middle  ear,  resembling  a  drum  in  being  closed  by  two  mem- 
branes, and  in  having  communication  with  the  atmosphere. 

U'vu-LA  (L.  uva,  a  grape).  The  small  pendulous  body  attached  to 
the  back  part  of  the  palate. 

VAS'CU-LAR  (L.  vas'culum,  a  little  vessel).  Pertaining  to,  or  contain- 
ing blood-vessels. 

VE'NOUS  (L.  v^na,  a  vein).  Pertaining  to,  or  contained  within  a 
vein. 

VEN-TI-LA'TION.  The  introduction  of  fresh  air  into  a  room  or  build- 
ing, in  such  a  manner  as  to  keep  the  air  within  it  in  a  pure  condi- 
tion. 

VEN-TRIL'O-QUISM  (L.  ven'ter,  the  belly,  and  lo'quw,  to  speak).  A 
modification  of  natural  speech  by  which  the  voice  is  made  to 
appear  to  come  from  a  distance.  The  ancients  supposed  that  the 
voice  was  formed  in  the  belly  ;  hence  the  name. 

VEN'TRI-CLES  of  the  heart.  The  two  largest  cavities  of  the  heart, 
situated  at  its  apex  or  point. 

VER'TE-BRAL  COLUMN  (L.  ver'tebra,  a  joint).  The  back-bone,  con- 
sisting of  twenty-four  separate  bones,  called  vertebrae,  firmly  jointed 
together ;  also  called  the  spinal  column  and  spine. 

VES'TI-BULE.  A  portion  of  the  internal  ear,  communicating  with  the 
semicircular  canals  and  the  cochlea ;  so  called  from  its  fancied 
resemblance  to  the  vestibule  or  porch  of  a  house. 

VIL'LI  (L.  vil'lus,  the  nap  of  cloth).  Minute  thread-like  projections 
found  upon  the  internal  surface  of  the  small  intestine,  giving  it  a 
velvety  appearance. 

VIT'RE-OUS  (L.  >oi'trum,  glass).  Having  the  appearance  of  glass ; 
applied  to  the  humor  occupying  the  largest  part  of  the  cavity  of 
the  eyeball. 

VIV-I-SEC'TION  (L.  vi'vvj,  alive,  and  se'co,  to  cut).  The  practice  of 
operating  upon  living  animals,  for  the  purpose  of  studying  some 
physiological  process. 

VOCAL  CORDS.  Two  elastic  bands  or  ridges  situated  in  the  larynx  : 
they  are  the  essential  parts  of  the  organs  of  tie  voice. 


INDEX 


A. 


PAGE 

.    97 
96 


Absorbent  vessels 

Absorption 

by  blood-vessels 

by  the  lacteals 96 

of  the  food 96 

Accommodation,  function  of 213 

Achilles,  tendon  of. 27 

Adam's  apple 229 

Air,  atmospheric 131 

Changes  in,  in  respiration 132 

Carbonic  acid  in 1:38 

Composition  of 131 

Dust  in  the 137 

Effects  of  impure 13!) 

Impurities  in 136 

Matters  in  the  expired 13-> 

Provision  for  purifying.     141 

Renovation  by  ventilation 142 

Air-cells  of  the  lungs 125 

Air-passages 125 

Albinos 44 

Albumen 58 

of  the  blood 102 

Albuminoid  substaiun-     57 

Varieties  of 57 

Properties  of. . . 57-58 

Albuminose.  ...    94 

Alcoholic  liquors 77 

Physiological  action  of 78 

Alinientary  canal. 81 

Animal  functions 148 

Animal  heat 143 

how  produced 143 

regulated   by  perspiration 145 

Animals,  relative  strength  of 28 

Apoplexy .% . .   171 

Aqueous  humor .' . .  210 

Arachnoid  membrane 152 

Arbor  vitse 154 

Arterial  blood ...  107-135 

differs  from  venous 135 

Arteries 114 

Arrangement  of 115 

Carotid 116 

Distribution  of 115 

Pulsation  of. 115 

Radial 116 

Temporal 116 

Arytenoid  cartilage 229 

Asphyxia 250 

Assimilation 80, 121 

Audition 215 

12 


^ 

Auditory  canal 218 

nerve 222 

Auricles  of  the  heart 109 

B. 

Back-bone 21 

Bathing 47 

Importance  of. 47 

Time  and  manner  of .49 

Baths 48 

Different  kinds  of 48 

Belladonna 206 

dilates  the  pupil 206 

Use  as  a  cosmetic 206 

Bile 95 

Secretion  of,  in  the  liver 95 

Accumulation  of,  in  the  gall-bladder  95 

Uses  of  95 

Biliary  duct .     95 

Bladder,  Gall- 95 

Bleeding,  how  stopped 121 

Blind-spot 207 

Blood 101 

Arterial 107-135 

Change  of  color 107 

Circulation  of. 107,  133 

Coagulation  of 105 

Composition  of 102 

corpuscles 102,  103 

fluid 105 

Microscopic  appearance  of 102 

Respiratory  changes  in 133 

Uses  of  the 105 

Venous 107,  135 

Blood-vessels 114,  118 

Absorption  by 96 

Injuries  to  the 121 

Body,  renovation  of  the (Hi 

Bones    15 

Form  and  composition  of 16 

Growth  of. 22 

Microscopic  structure  of 17 

Repair  of. 23 

Structure  of 17 

Uses  of 15 

Bowels 94 

Brain 150 

Anatomical  structure  of 152 

Function  of  the  172 

Injuries  of  the  173 

Membranes  of  the 152 

Reflex  action  of  the 174 


266 


INDEX. 


PAGE 

Bread 72 

Bronchial  tubes 125 

Bronchitis 128 

C. 

Canals,  Semicircular ..223 

Capillary  blood-vessels .'  118 

Circulation  in  the 118 

Carbonic  acid .   132 

exhaled  from  the  lungs 132 

in  the  air 138 

retention  in  tiie  blood 134 

Cartilage 20 

Arytenoid 229 

Cricoid  . .  229 

Thyroid 229 

Casein 58 

Cataract 210 

Cells,  Nerve  ...  150,  159 

Ciliated 128 

Cerebellum 153 

Function  of  the 172 

Cerebro-spinal  nervous  system 150 

Cerebrum .^ 152 

Function  of  tie 172 

Cheese 58 

Chest,  Framework  of. 19 

Contents  of  'th.e 19 

Chocolate : '. . .     77 

Chorea 169 

Choroid  coat  of  the  ?ye 204 

Chyle 95 

Chyme 94 

Cilia 128 

Circulation 107 

ill  the  frog's  foot 119 

of  the  blood 107 

Kapidity  of 120 

through  the  heart 112 

Through  the  lungs 123 

Clothing 51 

Coagulation  of  milk 58 

of  the  blood 104 

Cochlea 223 

Coflee 75 

Effects  of 75,  76 

Collar-bone 19 

Color-blindness 209 

Column,  Spinal 21 

Combustion,  Spontaneous 145 

Complexion 44 

Concha  of  the  ear 217 

Conjunctiva 200 

Contraction  of  heart Ill 

of  muscles 27 

Convulsions 169 

Cooking 70 

Cords,  Vocal 126,  230 

Cornea 203 

Corpuscles,  Blood 102 

Cosmetics 51 

Cranial  ganglia 150 

Functions  of 171 

Cranial  nerves 154 

Cranium 19 

Cricoid  cartilage 229 

Crystalline  lens 209 

Uses  of..,  ..  210 


PAGE 

Cuticle 41 

Function  of 183 

Cutis • 42 


D. 

Decussation  of  motor  and  sensory 

fibres  of  spinal  cord 164 

Dentition  of  infancy 82 

Diaphragm.  Movements  of  the,  in 

respiration 128,  129 

Diastole  of  the  heart Ill 

Diet,  Mixed 66,  85 

Necessity  for  changing 67 

Necessity  of  a  regulated 62 

The  best 63 

Digestion. 80 

Circumstances  affecting 97 

Gastric 93 

Intestinal 94 

Nature  of 81 

Organs  of 81-91 

Drownintr 250 

Duct,  Biliary 95 

Nasal 201 

Pancreatic 95 

Thoracic ' 97 

Dura  Mater. . .  . .  152 


B. 

Ear 217 

External 217 

Internal 222 

Middle 219 

Foreign  bodies  in 225 

Drum  of  the 219 

Bones  of  the 220 

Ear-sand 223 

Ear-stones 223 

Ear-wax 219 

Eggs 68 

Composition  of 68 

Emulsion  of  fats,  in  digestion 95 

Enamel  of  the  teeth 82 

Epiglottis 126,  229 

Uses  of 126,  2->0 

Eustachian  tube 221 

Exercise 30 

Different  modes  of 31 

Effects  of 30 

Importance  of. 30 

Open-air •. 

Expiration 128 

Movements  of. 12!) 

Extensor  muscles 2(» 

Eve 198 

Eyeball 20=3 

Eyelashes 200 

Eyelids 200 

F. 

Fats 59 

Emulsion  of 59 

Source  of,  in  food 59 

Fenestra  ovalis 224 

Fibres,  Muscular 25 


INDEX. 


267 


PAGE 

Fibres,  Nervous 149 

Fibrine  in  food 58 

of  the  blood 102 

Fish,  as  food 71 

Flexor  muscles   20 

Food 53 

Animal .   07 

Dai ly  quantity  of. 65 

Ingredients  of. 54-62 

Necessity  for 64 

Source  of 53 

Vegetable 71 


G. 

Gall-bladder 95 

Ganglia,  cranial.  Functions  of  the. .  171 
Gases,  Interchange  of,  in  the  lungs.  134 

Gastric  digestion 93 

Gactric  juice 91 

Action  of. 93 

Daily  quantity  of. 92 

General  sensibility 179 

Glands,  Perspiratory 45 

Salivary 86 

Sebaceous 44 

Glossary 252 

Glosso-pharyn^eal  nerve 189 

Gullet 90 

Gum..   61 

as  food 62 

Gustatory  nerve 189 

Gymnastics 33-38 

for  schools  and  colleges 33 


Hair 42 

Uses  of 44 

Hearing,  Sense  of 215 

Protection  of 2->4 

Heart 107 

Cavities  of  the 109,  110 

Circulation  through  the 112 

Frequency  of  action 112 

Movements  of  the Ill 

Valves  of  the  .. 112 

Heat,  Animal 143 

Production  of 143 

Regulation  of 145 

Hemiplegia 165 

Humor,  Aqueous 210 

Crystalline 209 

Vitreous 210 

Hunger 65 

Seat  of  the  sensation  of 65 

Hydra 149 

Hydrophobia 169 

Hygiene 1 

Hyperopia 212 


I. 

Incus 220 

Inorganic  substances  in  food 54 

Insalivation 86,  88 

Insensible  perspiration 46 


PAGE 

Inspiration 128 

Intestinal  juice 95 

Action  of 96 

Intestines 94 

Complete  digestion  in. the  small..  94 

Villiof  the 96 

Iris 205 

Function  of 205 

Iron 56 

Proportion  in  the  blood 57 

Proportion  m  the  food .  57 

J. 

Joints 19 

Varieties  of 20 

Juice,  gastric 91 

Intestinal 95 

Pancreatic...                    95 


Labyrinth 222 

Lachrymal  canals 201 

gland 201 

Lacteals 96 

Absorption  by 96 

Lactic,  acid  in  gastric  juice 92 

Lactometer 68 

Large  intestines 94 

Laryngoscope 231 

Larynx  125,  228 

Production  of  the  voice  in  the. 126,  228 

Lens,  crystalline 209 

Ligaments 19 

Light,  theory  of 197 

Lime  in  the  bones 16 

in  the  food 56 

Importance  of 56 

Liver  95 

Secretion  of  the 95 

Locked  jaw 169 

Long-sight , 212 

Lungs 123 

Capacity  of 130 

Structure  of 125 

Lymph 97 

Lymphatic  vessels 97 

M. 

Magendie,  on  pain 181 

Magnesia.  Compounds  of,  in  food...  57 

Malleus 220 

Marrow  of  the  bones 17 

Mastication 82 

Importance  of 88,  89 

Meats 68 

The  cooking  of. 69 

The  preservation  of 69 

Membrane  of  the  tympanum 219 

Medulla  oblongata 154 

Function  of  the 171 

Microscope 236 

The  value  of  the 236 

Simple 237 

Compound 239 

The  use  of  the...                 239 


268 


INDEX. 


PAGE 

Milk 68 

Composition  of 68 

Specific  gravity  of :...     68 

Milk-teeth 82 

Mucous  membrane  of  air  passages.  127 

Muscles 25 

Function  of  the 25 

Flexion  and  extension  of 26 

Voluntary  and  involuntary 26 

Muscular  contraction 27 

fibres 25 

sense 188 

Myopia 212 

N. 

Nails 42 

Uses  of  the 44 

Nasal  cavities 192 

duct • 201 

Nerve,  Auditory 222 

Glossopharyn-real 189 

Gustatory ~ 189 

Olfactory 193 

Optic 197 

Sympathetic 158 

Nerve  cells 150,  159 

Nerve  fibres 149 

Nerves,  Cranial 154 

Spinal _ 156 

Functions  of  the 160 

Sensory,  functions  of  the KiO 

Motor,  functions  of  the 160 

Sympathetic  system  of 158 

Nervous  system 148,  149 

Cerebro-spinal 150 

Nervous  tissue,  Properties  of 159 

Nose 192 

Nutrition,  Processes  of 80 

O. 

(Esophagus 90 

Oil,  Sources  of,  in  food 59 

Old-sight 215 

Olfactory  nerve 193 

Optic  nerve 197 

Orbicular  bone 220 

Orbit  of  the  eye 199 

Organic  substances  as  food 57 — 62 

Organs  of  circulation 107 

Digestion 81—91 

Respiration 123 

Sight : 198 

Voice 228 

Oxygen 131 

Amount  of,  consumed  in  respira- 
tion   132 

Continually  supplied  to  the  atmo- 
sphere    141 

P. 

Pain,  Relations  of,  to  pleasure 181 

Sensation  of 180 

Uses  of , 180 

Pancreatic  juice 95 

Usesof 95 


PAGK 

Pancreatin 95 

Paraplegia 163 

Parlor  gymnasium 36 

Passages,  Air 125 

Pelvis 19 

Pepsin 92 

Peristaltic  action  of  the  stomach..  92 

Peritoneum 94 

Perspiration,  Daily  amount  of 46 

Sensible  and  insensible 46 

Uses  of 46,  145 

Perspiratory  gland? 45 

Physical  strength 29 

Culture 33 

Physiology 11 

Animal 11 

Comparative 11 

Human 11 

Vegetable 11 

Pia  mater 152 

Plasma  of  the  blood. 102 

Pleura *. 124 

Pleurisy 128 

Pneumo  gastric  nerve 171 

Pneumonia 128 

Poisons  and  their  antidotes 247 

Potash  in  the  blood 57 

Potato.. .  73 

Presbyopia 215 

Preservation  of  the  teeth 85 

Ptyalin 88 

Pulsation  of  the  heart 113 

of  the  arteries 116 

Pulse 115 

Form  of  the 116 

Writer 116 

Pylorus 90 

R. 

Radial  artery 110 

Red  corpuscles  of  the  blood 102 

Reflex  action  of  the  spinal  cord  . .  .  165 

Requisites  for 167 

Usesof....: 167,  170 

Causing  convulsions 169 

Objects  of 170 

of  the  brain 174,  175 

Rennet 58 

Respiration 123 

Change  of  blood  in 123—133 

Frequency  of 129 

128 
123 
123 
135 
33 
206 
207 


Movements  of. 

Object  of 

Organs  of 

Respiratory  labor. 
Rest,  necessity  for 

Retina 

Retinal  light 


Ribs,  Movements  of,  in  respiration.  128 


S. 


Saccharine  substances 60 

Saliva 86 

Importance  of. 88 

Secretion  of 86 

Salivary  glands 86,  87 


INDEX. 


PAGE 

Salt,  Common 55 

Importance  of 56 

Sclerotic  coat  of  the  eyeball 204 

Sebaceous  glands 44 

Secretion  of 45 

Semicircular  canals 223 

Sensation  of  pain 180 

Relations  of,  to  pleasure 181 

of  temperature  187 

of  weisrht  188 

Modification  of : 178 

Production  of 177 

Variety  of 178 

Sense  of  hearing 215 

sight 196 

smell 192 

taste 189 

touch 184 

Sense,  muscular 188 

thermal 187 

Senses,  Special 177 

Sensibility,  General 179 

Short-sight 212 

Sinews 27 

Sight,  Sense  of 196 

Organs  of 198 

Skeleton 19 

Skin 41 

Structure  of 41 

Skull !.     19 

Uses  of  the 19 

Sleep,  Necessity  for 38 

Amount  required ,    39 

Small  intestines 94 

Smell,  Sense  of 192 

Nerve  of 193 

Uses  of 194 

Soda  in  the  food 57 

Sound,  Production  of 215 

Special  senses 177 

Spectroscope . .  104 

Speech 227 

Relation  of,  to  the  sense  of  hear- 
ing    228 

Sphygmograph 116 

Spinal  column 21 

Spinal  cord.. 155 

Decussation  of  the 164 

Direction  of  fibres  in 164 

Functions  of  the 162 

Nerves  of 156 

Reflex  action  of 165 

Spontaneous  combustion 145 

Stapes 220 

Starch el 

Its  change  into  sugar 61 

Different  kinds , 61 

Effect  of  boiling 61 

Microscopic  appearance 61 

Stimulating  substances 62 

Stomach 90,  92 

Digestion 93 

Movements  of 92 

Secretion  of 92 

St.  Vitus' dance 169 

Sugar 60 

Varieties 60 

Sources  of 61 


PAGE 

Sun-bath 59 

Sympathetic  system  of  nerves 158 

Synovia 20 

Systole  of  the  heart m 

T. 

Taste,  Association  of 190 

Education  of. '. .'  191 

Organ  of 188 

Sense  of 189 

Tea,  Effect  of 76 

Kinds  of 1b 

Tears 201 

Escape  of  the 201 

Teeth 82 

Temporary  set  of 82 

Permanent  set  of 83 

Bicuspid 83 

Canine , 83 

Incisor 83 

Molar 84 

Arrangement  of 85 

of  different  animals 85 

Preservation  of 85 

Temperature  of  the  body 140 

Extremes  of '   146 

Sensations  of 187 

Tendon  of  Achilles 27 

Tendons 27 

Tetanus 169 

Thermal 50 

Thermae  sense 187 

Thirst 65 

Thoracic  duct 97 

Thorax 19 

Thyroid  cartilage : 229 

Tissues,  intimate  structure  of  the. .  236 

Human 244 

of  the  lower  animals 245 

Tongue 188 

Nerves  of 189 

Sensibility 189 

Touch,  Delicacy  of 186 

Organs  of 183 

Sense  of 184 

Trachea 125 

Transfusion  106 

Trichina  spiralis 71 

Trunk 19 

Tympanum  of  the  ear 219 

Membrane  of 219 

V. 

Valves  of  the  heart. . .  ..  112 

of  the  veins 117 

Vapor,  Animal,  in  breath 132 

Vegetable  food 71 

Vegetative  functions 148 

Veins 117 

Valves  of 117 

Venous  blood 135 

Changes  of,  in  respiration 133 

Ventilation 142 

Ventricles  of  the  larynx 229 

of  the  heart 110 

Ventriloquism 235 


270 


I^DEX. 


PAGE 

Vertebrae 21 

Vestibule  of  the  internal  ear 223 

Villi  of  the  intestines 96 

Absorption  by 96 

Vital  knot  171 

Vitreous  humor 210 

Vocal  cords 126,  230 

Observation    of,    with    laryngo- 
scope   231 

Voice 227 

Organ  of 228 

Production  of 232 

Varieties  of 233 


W.  PAGE 

Water 74 

Action  of,  on  lead 75 

Chemically  pure 74 

Croton 74 

exhaled  with  the  breath 132 

from  springs  and  well? 7i 

Proportion  of,  in  the  blood 55 

of,  in  the  tissues  and 

fluids  of  the  body 54 

Ridgewood 74 

Walking,  as  a  means  of  exercise. . .  31 

White  corpuscles  of  the  blood 104 

Wisdom  teeth 84 


ANDERSON'S    SCHOOL    HISTORIES. 


PRACTICAL- BOOKS  BY  A  PRACTICAL  TEACHER. 


A  Grammar-School  History  of  the  United  States. 

By  JOHN  J.  ANDERSON,  A.M.,  late  Principal  of  Grammar  School  Nt 
31,  New  York  City;  Author  of  a  Manual  of  General  History,  A  Picto- 
rial School  History  of  the  United  States,  etc.,  etc.  Illustrated  with 
more  than  40  Maps.  16mo.  258  pages. 

CHARACTERISTIC  FEATURES. — 1.  The  narrative  is  written  with  great  clearness  and 
conciseness,  and  is  brought  down  to  the  present  time.  2.  Unimportant  matters  are  en- 
tirely omitted,  or  only  incidentally  alluded  to.  3.  The  history  and  the  geography  are 
taught  together.  4.  Th-  hook  is  fully  supplied  with  Maps,  and  the  location  of  every 
place  mentioned  is  ace'  ately  shown.  5.  All  the  proper  names  are  accurately  pronounced 
in  connection  with  th'  lames  as  they  occur.  6.  The  plan  affords  frequent  and  systemarfc 
reviews  by  topics.  Two  entirely  different  sets  of  question^  run  through  the  book. 
8.  It  contains  the  Constitution  of  the  United  States,  with  full  explanations  and  class- 
exercises.  9.  It  contains  Washington's  Farewell  Address.  10.  It  contains,  at  the  close 
of  the  book,  a  complete  resume  of  the  whole  history,  arranged  for  topical  study  and 
recitation.  11.  It  contains  but  260  pages.  1-2.  It  is  sold  at  a  moderate  price. 

The  publishers  believe  that  teachers  who  are  tired  of  the  cumbersome  histories  of  our 
country  now  largely  in  use,  and  desire  a  book  with  which  they  can  produce  satisfactory 
results,  will  find  that  this  work  icill  exactly  meet  their  wants. 

DEPARTMENT  OP  PUBLIC  INSTRUCTION, 

Superintendents  Office,  City  of  New  York. 

41 1  have  carefully-examined  Anderson's  Histories,  adopted  by  the  Board  of  Education, 
and  used  in  the-Public  Schools  of  this  city,  and  cheerfully  commend  them  to  the  favorable 
regard  of  teachers  and  School  officers,  as  well  adapted  to  the  purposes  of  instruction  in 
this  branch  of  study,  and  as  excellent  and  comprehensive  compendium?  of  the  leading 
events  of  history."  S.  S.  RANDALL,  Svp't  of  Schools. 

"Anderson's  Histories  have  been  in  use  in  the  Grammar  Schools  of  this  city  from  the 
date  of  their  publication,  and,  as  far  as  I  know,  have  given  the  highest  degree  of  satisfac- 
tion. They  are  written  in  a  clear,  concise  style,  are  unusually  accurate,  and  abound  in 
exercises  which  only  a  practical  teacher  could  have  constructed,  and  which  make  them 
invaluable  Class  Manuals.  They  can  scarcely  fail  to  prove  acceptable  wherever  practi- 
cally tried."  HENRY  KIDDLE,  Ass't  Sup't  of  Scliools. 

From  Fifty -seven  Principals  of  Grammar  Schools  in  the  City  of  Neio  York. 
"We  are  using  Anderson's  Histories  in  our  school?  with  complete  success.    For  class- 
room instruction  they  are,  we  believe,  superior  to  any  other  works  on  the  subject  with 
which  we  are  acquainted." 

DEPARTMENT  OP  PUBLIC  INSTRUCTION, 

Superintendent's  Office,  Brooklyn. 

"This  is  to  certify  that  I  am  well  acquainted  with  Anderson's  Historic!-,  they  having, 
been  in  the  Public  Schools  of  this  city  during  the  last  three  years.  After  having  seen  a 
variety  of  works  on  the  subject  tried  here,  I  am  confident  that  ANDERSON'S  are  decidedly 
the  best  for  class-room  instruction.  They  give  the  teacher  just  the  aid  he  needs  to 
produce  satisfactory  results,  and  I  therefore  give  them  my  unqualified  recommendation." 

J.  W.  BULKLEY,  Sup't  of  Schools. 

"  Mr.  Anderson  has,  I  think,  found  the  golden  mean  in  nearly  every  feature  that  should 
characterize  a  judicious  school  history." 

JAMES  CRUIKSHANK,  AssH  Sup't  of  Schools. 

From  the  Principals  of  the  Grammar  Schools  in  the  City  of  Brooklyn. 

"It  gives  us  pleasure,  after  using  Anderson's  Histories  in  our  schools  during  the  last 

two  years,  to  say  that  we  like  them.    The  plan  of  instruction,  combining  the  geography 

with  the  chronology  of  the  narrative,  is  one  which  gives  the  books  a  decided  superiority 

over  the  works  of  other  authors  on  the  subject.    Tfiey  have  our  hearty  commendation." 


PUBLISHED  BY  CLARK  &   MAYNARD,  NEW  YORK. 


36098 


ANDERSON'S    SCHOOL    HISTORIES. 


A  School  History  of  England. 


Illustrated  with  Maps.  By  JOHN  J.  ANDERSON,  A.M.,  Author  of  a 
Grammar  School  History  of  'the  United  States,  a  Pictorial  School  History  of 
the  United  States,  a  Manual  of  General  History,  etc.,  etc.  12mo.  302  pages. 
Price  $1.60. 

1.— One  of  the  aims  of  the  author  is  to  give  not  only  the  political  and  military  history 
of  the  country,  but  also  to  show  its  progress  from  time  to  time  in  civilization.  2. — The 
pronunciation  of  proper  names  is  given  in  connection  with  the  names  as  they  occur. 
3.— In  addition  to  the  maps  with  the  text,  the  work  contains  six  finely  engraved  and 
beautifully  colored  historical  maps,  showing  the  geographical  changes  in  the  country  at 
•different  periods  in  its  history.  4.— An  Appendix  contains  an  exposition  of  the  leading 
features  of  the  English  Constitution,  and  a  geographical  and  historical  account  of  the 
British  Possessions.  5. — The  work  ia  fully  supplied  with  Chronological  and  Genealogical 
Table's,  Biographical  Notes,  Subjects  topically  arranged  by  means  of  Review  Questions 
and«n  Pronouncing  Index.  6.— The  volume  embraces  only  300  pages,  and  may  therefore 
be  easily  co 


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544488 


UNIVERSITY  OF  CALIFORNIA  LIBRARY 


or  tne  biography  of  the  mostaistinguislied  men  or  tne  couiur^  wnicii  will 
very  much  tend  to  excite  a  wish  for  additional  reading  and  knowledge.  A  pretty 
thorough  examination  of  the  work  leads  us  to  the  opinion  that  its  excellence  leaves 
little  to  be  desired  in  a  school  history.  If  we  could  have  had  such  a  book  at  the  right 
time,  in  our  school-days,  it  would  have  saved  us  a  great  deal  of  valuable  time. 
Frpm  Prof.  EBEN  S.  STEARNS,  Principal  of  the  Robinson  Female  Seminary.  Exeter,  N.  H. 
Prof.  Anderson's  History  of  England  seems  to  me,-as  the  result  of  a  close  examina- 
tion, eminently  adapted  to  the  school-room.  Conscious,  apparently,  that  a  compend  of 
history  must,  from  the  nature  of  the  case,  exclude  much  of -"narrative  and  interesting 
detail,  the  author  has,  with  remarkable  skill  and  judgment,  stised  upon  the  most  salient 
points  and  presented  them  in  such  appropriate  and  forcible  language,  and  so  happily, 
that  the  student  is  beguiled  through  the  driest  abstractions,  in  this  concise,  yet  vivid. 
manner,  all  that  is  essential  to  a  general  knowledge  of  English  history  is  ottered  for  study 
within  limits  which  can  be  readily  conlpassed  by  the  circumstances  of  most  schools  and 
seminaries.  The  well  drawn  maps  connecting  geography  with  history,  the  carefully 
arranged  chronological  tables  with  which  the  work  abounds, and  the  pronunciation  of 
proper  names  constitute  also  distinctive,  and  most  valuable  features.  The  introduction 
of  dates,  of  course  not  to  be  dispensed  with,  has  been  so  arranged  as  not  to  interfere 
with  the  narrative,  or-to  unncessarily  burden  the  student's  memory.  Certainly,  no  other 
work  of  the  kind,  which  I  have  ever  examined,  has  impressed  me  so  favorably  as  this ; 
and  I  shall  be  much  disappointed  if  it  does  not  so  commend  itself  to  teachers  as  to 
speedily  obtain  the  very  highest  place  among  text-books. 


Published  by  CLARK  &  MAYNARD,  New  York, 


